Clinical UM Guideline

 

Subject: Continuous Interstitial Glucose Monitoring
Guideline #:  CG-DME-38 Publish Date:    12/27/2017
Status: Revised Last Review Date:    02/02/2017

Description

This document addresses the use of continuous interstitial glucose monitoring devices, also referred to as CIGM or CGM devices, which are used to assist in the management of some forms of diabetes.

Note: For information regarding the use of external insulin pumps, please see:

Clinical Indications

Medically Necessary:

Professional, intermittent, short-term use of continuous interstitial glucose monitoring devices as an adjunct to standard care is considered medically necessary in the care of individuals with type 1 diabetes, when all of the following criteria are met:

  1. Inadequate glycemic control despite compliance with frequent self-monitoring (at least 4 times per day) and including fasting hyperglycemia (greater than 150 mg/dl) or recurring episodes of severe hypoglycemia (less than 50 mg/dl). This poor control is in spite of compliance with multiple alterations in self-monitoring and insulin administration regimens to optimize care; and
  2. Insulin injections are required 3 or more times per day or an insulin pump is used for maintenance of blood sugar control; and
  3. Four or more fingersticks are required per day; and
  4. Monitoring and interpretation are under the supervision of a physician; and
  5. The device is only used for 6, 7, or 14 consecutive days on an appropriate, periodic basis.

Personal long-term use of continuous interstitial glucose monitoring devices as an adjunct to standard care is considered medically necessary for any of the following:

  1. Adults (greater than or equal to 25 years old) with type 1 diabetes who meet the following criteria:
    1. Inadequate glycemic control, demonstrated by HbA1c measurements between 7.0% and 10.0%, despite:
      1. Compliance with frequent self-monitoring (at least 4 times per day); and
      2. Multiple alterations in self-monitoring and insulin administration regimens to optimize care; and
    2. Insulin injections are required 3 or more times per day or a medically necessary insulin pump is used for maintenance of blood sugar control; or
  2. Individuals, regardless of age, with type 1 diabetes who meet the following criteria:
    1. Recurring episodes of severe hypoglycemia (less than 50 mg/dl); and
    2. Inadequate glycemic control despite:
      1. Compliance with frequent self-monitoring (at least 4 times per day); and
      2. Multiple alterations in self-monitoring and insulin administration regimens to optimize care; and
    3. Insulin injections are required 3 or more times per day or a medically necessary insulin pump is used for maintenance of blood sugar control; or
  3. Individuals with type 1 diabetes who are pregnant, during the course of the pregnancy, who meet the following criteria:
    1. Inadequate glycemic control despite compliance with frequent self-monitoring (at least 4 times per day) and including fasting hyperglycemia (greater than 150 mg/dl) or with recurring episodes of severe hypoglycemia (less than 50 mg/dl). This poor control is in spite of compliance with multiple alterations in self-monitoring and insulin administration regimens to optimize care; and
    2. Insulin injections are required 3 or more times per day or a medically necessary insulin pump is used for maintenance of blood sugar control; and
    3. Four or more fingersticks are required per day.

Not Medically Necessary:

Use of continuous interstitial glucose monitoring devices is considered not medically necessary for all other indications, including but not limited to:

  1. When the criteria above have not been met.
  2. Individuals with type 2 diabetes.
Coding

The following codes for treatments and procedures applicable to this guideline are included below for informational purposes. Inclusion or exclusion of a procedure, diagnosis or device code(s) does not constitute or imply member coverage or provider reimbursement policy. Please refer to the member's contract benefits in effect at the time of service to determine coverage or non-coverage of these services as it applies to an individual member.

CPT

 

95249

Ambulatory continuous glucose monitoring of interstitial tissue fluid via a subcutaneous sensor for a minimum of 72 hours; patient-provided equipment, sensor placement, hook-up, calibration of monitor, patient training, and printout of recording

95250

Ambulatory continuous glucose monitoring of interstitial tissue fluid via a subcutaneous sensor for a minimum of 72 hours; physician or other qualified health care professional (office) provided equipment, sensor placement, hook-up, calibration of monitor, patient training, removal of sensor, and printout of recording

95251

Ambulatory continuous glucose monitoring of interstitial tissue fluid via a subcutaneous sensor for a minimum of 72 hours; analysis, interpretation and report

 

 

HCPCS

 

A9276

Sensor; invasive (e.g., subcutaneous), disposable, for use with interstitial continuous glucose monitoring system, 1 unit = 1 day supply

A9277

Transmitter; external, for use with interstitial continuous glucose monitoring system 

A9278

Receiver (monitor); external, for use with interstitial continuous glucose monitoring system

A9279

Monitoring feature/device, stand-alone or integrated, any type, includes all accessories, components and electronics, not otherwise classified

K0553

Supply allowance for therapeutic continuous glucose monitor (CGM), includes all supplies and accessories, 1 month supply = 1 unit of service [that is, a device that does not require a finger stick, e.g., Dexcom G5]

K0554

Receiver (monitor), dedicated, for use with therapeutic glucose continuous monitor system [that is, a device that does not require a finger stick, e.g., Dexcom G5]

S1030

Continuous noninvasive glucose monitoring device, purchase

S1031

Continuous noninvasive glucose monitoring device, rental, including sensor, sensor replacement, and download to monitor

 

 

ICD-10 Diagnosis

 

 

All diagnoses

Discussion/General Information

According to the American Diabetes Association, diabetes is one of the most common chronic diseases in the United States, with approximately 30 million Americans with diagnosed disease.  Another 8 million are believed to have undiagnosed disease.

Devices are available that continuously monitor glucose concentrations in the fluid in between the body's cells, also known as interstitial fluid.  Such devices have been proposed as an adjunct to routine blood-based glucose measurements in individuals with trouble maintaining appropriate blood glucose levels despite frequent blood-based monitoring or those with frequent undetected hypoglycemic events. 

Such devices are referred to as continuous interstitial glucose monitoring (CIGM) devices and are designed to provide real-time interstitial glucose measurements, which have been found to accurately reflect blood glucose levels.  Furthermore, such devices have special features such as low and high glucose concentration alarms and data storage for later analysis.  The stored data has been shown to be useful in identifying ways to improve individual care by altering diet, exercise, medication types, and timing of insulin administration. 

There are a wide variety of interstitial glucose monitoring devices available.  These devices can be divided into those intended for professional or personal use.  Professional use involves periodic monitoring with retrospective review of the data by a medical provider and those intended for longer-term real-time use by the individual.  There are several devices on the market that allow for 6, 7, and 14 day monitoring intervals.

As noted above, short-term use devices are intended to be used periodically, and are usually dispensed by the treating provider who then collects, analyzes and interprets the resultant data in a retrospective manner.

Personal CIGM devices involve long-term use, are usually purchased by the individual for whom it has been prescribed, and are intended to be used continuously in real-time to help guide daily care.  Periodic data downloading and analysis by the individuals and/or provider may also occur and provide additional data to guide care.

Meta-Analyses Data

The use of CIGMS for the monitoring and treatment of type 1 diabetes has been the topic of many studies.  These studies have investigated the use of these devices in several different populations, including children, individuals with difficulty with controlling their conditions, and pregnant women with diabetes.  These studies have subsequently been subject to additional meta-analyses.  A meta-analysis published in 2011 by Gandhi and colleagues identified studies conducted among individuals with type 1 and/or type 2 diabetes and stratified findings by type of diabetes.  The investigators identified 19 randomized controlled trials (RCTs) involving 1801 subjects using CIGM devices for at least 8 weeks in the outpatient setting.  Overall, the authors reported that, when compared with self-monitoring of blood glucose, CIGM was associated with a statistically significant reduction in mean HbA1c (weighted mean difference [WMD], -0.27%; 95% confidence interval [CI], -0.44% to -0.10%).  When stratified by age and type of diabetes, there was a statistically significant reduction in HbA1c in adults with type 1 diabetes and adults with type 2 diabetes, but not in studies of children and adolescents with type 1 diabetes.  They concluded that CIGM appears to help improve glycemic control in adults with type 1 and type 2 diabetes, but its impact on hypoglycemic events is unclear.  They recommended larger trials with longer follow-up be conducted.

Langendam and others (2012) published a Cochrane library review on the use of CIGM systems for type 1 diabetes mellitus.  A total of 22 studies met their inclusion criteria.  They observed that after 6 months of CIGM treatment there was a significant larger decline in HbA1c level for real-time CIGM users starting insulin pump therapy compared to individuals using multiple daily injections (MDI) and self-monitoring of blood glucose (SMBG).  The risk of hypoglycemia was increased for CIGM users, but CIs were wide.  For individuals starting with CIGM only, the average decline in HbA1c level 6 months after baseline was significantly larger for CIGM users compared to SMBG users, but much smaller than for individuals starting using an insulin pump and CIGM at the same time.  On average, they reported not finding a significant difference in risk of severe hypoglycemia or ketoacidosis between CIGM and SMBG users.  The authors' conclusions included observations that there is limited evidence for the effectiveness of real-time CIGM use in children, adults and individuals with poorly controlled diabetes.  The largest improvements in glycemic control were seen for sensor-augmented insulin pump therapy in subjects with poorly controlled diabetes who had not used an insulin pump before.  Finally, they stated that there are indications that higher compliance of wearing the CIGM device improves glycosylated hemoglobin A1c level (HbA1c) to a larger extent.

Another meta-analysis was published by Floyd (2012) that included 14 studies involving 1188 subjects with type 1 diabetes.  The reported findings included that compared with SMBG, the use of CIGM was associated with a greater reduction in HbA1c (p<0.000)], but the number of hypoglycemic events reported was not significantly different between the CIGM and SMBG groups (p=0.5).  The duration of hypoglycemia was noted to be shorter in the CIGM group (p<0.0001), which also experienced a shorter duration of hyperglycemia than SMBG (p=0.04).  They concluded that the use of CIGM is associated with improvement in metabolic control in type 1 individuals, with significant short- and long-term reductions in HbA1c and reduction in the duration of periods of hypoglycemia and hyperglycemia vs. SMBG.

Yeh and others (2012) conducted a meta-analysis involving eight studies of subjects with type 1 diabetes receiving at least 12 weeks of treatment with either real-time CIGM or SMBG.  The authors reported that CIGM use resulted in greater reductions in HbA1c vs. SMBG, but no differences in the occurrence of hypoglycemia.  They noted that when looking at studies with younger age groups, one study reported beneficial outcomes while four others did not.  Overall, the meta-analysis of these five studies showed no mean between-group differences in HbA1c levels.  A similar analysis of three studies involving adults found significant between-group differences in HbA1c levels in favor of the CIGM group.  Seven studies were included in an analysis of time spent within a hyperglycemic range.  It was reported that the use of CIGM resulted in significant improvements in this measure, with a mean between-group difference of -68.56 minutes/day.

Poolsup (2013) reported a meta-analysis of RCTs involving pediatric individuals with type 1 diabetes (10 studies n=817) and adults with type 2 diabetes (5 studies, n=161).  Inclusion criteria included subjects undergoing treatment at least 8 weeks in duration and with HbA1c used as an outcome.  The authors reported that for subjects with type 1 diabetes, the use of CIGM did not have a significant impact on HbA1c when compared to SMBG.  The pooled estimate of the difference in HbA1c between groups was -0.13% (95% CI, -0.38% to 0.11%).  In a subgroup analysis, the authors stated that subjects using devices providing data retrospectively did not result in better glucose control than SMBG.  However, they found that the use of real-time CIGM was superior to SMBG in terms of improving glycemic control.

With regard to individuals with type 2 diabetes specifically, the Ghandi study mentioned above included three RCTs that included subjects with type 2 diabetes.  These studies involved heterogeneity with regard to inclusion of subjects who did and did not require insulin therapy.  Their meta-analysis of the three trials indicated statistically significant reductions in HbA1c with CIGM vs. SMBG.  Likewise, the study by Poolsup previously described involved a meta-analysis of four trials including adults with type 2 diabetes. In their analysis, CIGM appeared to result in improved HbA1c reductions compared to SMBG, with a pooled mean difference of -0.31% (p=0.04).  These studies reported the use of different types of devices (for example, retrospective CIGM vs. real-time CIGM) and significant variability in frequency of CIGM use. 

Representative RCTs Addressing CIGM for Type 1 Diabetes

An article by the Juvenile Diabetes Research Foundation (JDRF) Continuous Glucose Monitoring Study Group (Tamborlane, 2008) describes a controlled trial of 322 subjects with type 1 diabetes randomized to receive either standard care with blood glucose monitoring (n=165) or to CIGM combined with blood glucose monitoring (n=157).  The study stratified the participants into three groups; children 8-14 years of age (n=114), adolescents and young adults 15-24 years of age (n=100), and adults 25 years old and above (n=98).  The adult group demonstrated the most significant differences between the control and study populations at the 26-week follow-up point.  When compared to the control group, the CIGM group in this age group had significantly better results compared to the standard care group in regard to almost all measures of glycemic control, including: overall HbA1c change from baseline to 26 weeks (p<0.001) improved, relative reduction in HbA1c of 10% or more (p=0.003), number of subjects achieving target HbA1c goals less than 7.0% with no severe hypoglycemic events (p=0.006), and higher percentage of time within normal blood glucose range (p<0.001).  The data for the 8-14 year old age group demonstrated a significantly greater relative reduction in HbA1c of 10% or more (p=0.04) and a higher percentage of subjects achieving an HbA1c less than 7.0% (p=0.01).  The 15 to 24 year old group had no significant differences noted.  The findings of this study suggest that CIGM may provide benefit for adults over age 24 and, to a lesser degree, children and adolescents under age 15.  The authors note that the rate of sensor use between age groups may be related to the differences in clinical outcomes.  The group with the least reported benefits, the 15-24 years-old, had only a 30% sensor use frequency.  The group with the most benefit, those 25 years of age and older had the highest use of sensor frequency at 83%.  The group with intermediate results, 8-14 years-old, had an intermediate frequency of use of 50%.  The rate of parental supervision and support for CIGM was greater for the 8-14 years age group than for the 15-24 year old group, which may explain the higher rate of utilization and the significantly better results in younger children.  The findings of this study suggest that significant benefits may be gained with CIGM when a high level of compliance with therapy is achieved.  It should be noted that this study population was composed of highly motivated individuals who measured their blood glucose levels 5 times a day or more, and had a beginning HbA1c of 10% or less. 

In an extension study of the study reported by Tamborlane, 214 of 219 (98%) control group subjects were followed for an additional 6 months and asked to use CIGM daily (JDRF, 2010).  This included 80 subjects who were at least 25 years old, 73 who were 15-24 years old, and 61 who were 8-14 years old.  Among the 154 subjects with baseline HbA1c at least 7%, there was a significant decrease in HbA1c at 6 months after CIGM use in the older age group (mean change in HbA1c, -0.4% ± 0.5%, p=0.003).  There was a significant treatment group difference favoring the CIGM group in mean HbA1c at 26 weeks adjusted for baseline values.  The authors concluded that the weight of evidence suggests that CIGM is beneficial for individuals with type 1 diabetes who have already achieved excellent control with HbA1c of less than 7.0% with SMBG.

In a four-arm multi-centre study in the UK, 404 adult subjects (median age 52 years) with poorly controlled (HbA1c greater than 7.5%) type 1 (58%) or type 2 (42%) diabetes taking at least two daily insulin injections (2% used an insulin pump) were randomized into four groups and followed for 18 months (Cooke, 2009; Newman, 2009).  The first group was managed with short-term intermittent interstitial glucose monitoring (Mini Med CGMS, Medtronic Northridge, CA) and wore the device three times for 72 hours during the first 3 months of the trial and on another three occasions thereafter.  The second group was managed with the GlucoWatch G2 Biographer (Animas Corporation, West Chester, PA; market withdrawal July 2007).  This group wore the device at least 4 times per month and a maximum of 4 times per week during the first 3 months and then as desired for the remainder of the 18-month trial.  Glucose data was downloaded by trained diabetes nurses and used to guide therapy adjustments.  A third group served as an "attention control" and these subjects attended scheduled visits at 4, 8, and 12 weeks where self-monitored blood glucose data were reviewed and used to adjust therapy.  The fourth group served as a standard control and these subjects attended clinic visits and performed self-monitoring at their usual frequency.  The primary outcome measure in this study was reduction in HbA1c from baseline to 18 months.  The study showed no significant improvement in HbA1c in either device group compared with standard care.  The percentage of individuals achieving a 12.5% or greater reduction in HbA1c from baseline was 15% (GlucoWatch), 27% (CIGM), 27% (attention control) and 23% (standard care).  The study did demonstrate that the percentage of total readings in the hypoglycemic range was lower in the standard care control group.  At week 26, the standard control subjects were 30% less likely than the GlucoWatch group, but not the CIGM group, to have a hypoglycemic episode.  The use of both devices declined throughout the study.  By 18 months, 33% of the CIGM group and 80% of the GlucoWatch group had stopped using the device.  This study was not adequately powered to perform subgroup analysis.  Limitations of the study include its heterogeneous subject mix, on a variety of treatment regimens, and high drop-out rate. 

In another study comparing SMBG to CIGM, Raccah et al. (2009) followed two groups of subjects in a parallel open label study of 115 individuals with type 1 diabetes.  The authors reported that in a subgroup of 91 subjects fully compliant with the study protocol, CIGM demonstrated significantly better improvement in HbA1c measurements when compared to those in the MDI group (p=0.004).  No differences between groups were reported in the incidence of hypoglycemia.  Using the same age thresholds used in the JDRF study described above, the authors conducted a post-hoc analysis of CIGM compliance.  As in the 2010 JDRF study, the highest compliance was found in the greater than 25 year old adult cohort (n=25, sensor wear 74.9% of the time), followed by children age 5-14 years (n=14, sensor wear 68.4% of the time).  The adolescent and young adult cohort age 15-25 years (n=15, sensor wear 52.4% of the time) had the lowest CIGM compliance.  Given the small sizes of the age cohorts, HbA1c improvement comparisons were not significantly different between CIGM and MDI for any age subgroup.

The results of the Diabetes Research in Children Network (DirecNet) Study Group RCT were published by Mauras in 2011.  This study evaluated the use of CIGM in the management of young children aged 4 to younger than 10 years with type 1 diabetes.  In this study, 146 children were assigned to either CIGM or usual care.  At baseline, 30 children (42%) had an HbA1c of at least 8%.  The primary outcome was reduction in HbA1c by at least 0.5% without the occurrence of severe hypoglycemia at 26 weeks.  The authors reported that 19% in the CIGM group and 28% in the usual care group (p=0.17) met this endpoint. Mean change in HbA1c, a secondary outcome, did not differ significantly between groups (-0.1 in each group, p=0.79).

An RCT published by Battelino (2011) involving 120 children and adults on intensive therapy for type 1 diabetes HbA1c < 7.5% were assigned to either SMBG with a masked CIGM every second week for 5 days (n=58) or real-time CIGM (n=62).  The authors reported that the time per day spent in hypoglycemia was significantly shorter in the CIGM group vs. the control group (p=0.03).  HbA1c at 26 weeks was lower in the CIGM group than in the control group (p=0.008).  The time spent in the 70 to 180 mg/dL normoglycemia rage was significantly longer in the CIGM group vs. the control group (mean hours per day, 17.6 vs. 16.0, p=0.009).  The authors concluded that CIGM was associated with reduced time spent in hypoglycemia and a concomitant decrease in HbA1c in children and adults with type 1 diabetes.

Another RCT published by this group involved 153 children and adults with type 1 diabetes receiving regular care with an insulin pump and who had HbA1c between 7.5-9.5%.  Subjects were assigned to receive care with their insulin pump with a connected CIGM device with the sensor either on or off for 6 months.  Following the initial 6 months, participants underwent a 4 month-long washout period and then were crossed over to the other treatment arm for 6 months.  The initial assignments included 77 subjects in the sensor-on group and 76 to the sensor-off group.  At the end of the trial period, the mean difference in HbA1c was -0.43% in favor of the sensor-on arm (p<0.001).  Following cessation of glucose sensing, HbA1c reverted to baseline levels.  The authors reported that less time was spent with sensor glucose < 3.9 mmol/l during the sensor-on period than in the sensor-off period (19 vs 31 min/day; p=0.009).  The mean number of daily boluses increased in the sensor-on group (p<0.0001), together with the frequency of use of the temporary basal rate (p<0.0001) and manual insulin suspend (p<0.018) functions.  No differences between groups were reported with regard to severe hypoglycemic events (p=0.40).  The authors concluded that CIGM was associated with decreased HbA1c levels and time spent in hypoglycemia in individuals with type 1 diabetes using insulin pump therapy.  More frequent self-adjustments of insulin therapy may have contributed to these effects.

In 2017 Beck and colleagues reported on the results of the DIAMOND RCT.  This study included 158 adults with type 1 diabetes using multiple daily insulin injections and with HbA1c levels of 7.5% to 9.9%.  All Subjects were randomized in a 2:1 fashion to receive treatment with either CIGM (n=105) or standard care (n=53).  HbA1c level, the primary outcome measure, was measured in a centralized lab from baseline to 24 weeks.  A total of 155 (98%) of subjects completed the study (n=102 for the CIGM group [97%], n=53 for the control group [100%]).  Median CIGM use in the experimental group was 7 days a week at a 4, 12, and 24 weeks, with only 2 subjects discontinuing CIGM use prior to 24 weeks.  In the CIGM group, mean HbA1c was reduced 1.1% at 12 weeks and 1.0% at 24 weeks.  In the control group mean HbA1c reduction 0.5% and 0.4%, respectively (between group difference at 24 weeks, p<0.001).  The adjusted difference in mean change in HbA1c level from baseline to 24 weeks in the CIGM group was -0.6% (p<0.001).  The median duration of hypoglycemia at a blood glucose concentration of less than <70 mg/dL was 43 min/day in the CIGM group vs. 80 min/day in the control group (p=0.002).  Additional significant differences between groups at 24 months in favor of the CGIM group were noted for glucose variability (coefficient of variation 36 vs. 42, p<0.001), minutes per day with blood glucose concentration within range (736 minutes vs. 650, p=0.005), and median duration of hypoglycemia at blood glucose concentration less than >180 mg/dL (638 minutes vs. 740, p=0.03).  The occurrence of severe hypoglycemia events did not differ between groups, with 2 events reported in each group.  The authors concluded that, "Among adults with type 1 diabetes who used multiple daily insulin injections, the use of CGM compared with usual care resulted in a greater decrease in HbA1c level during 24 weeks."  They further commented that, "Further research is needed to assess longer-term effectiveness, as well as clinical outcomes and adverse effects."

Also in 2017, Lind and colleagues published the results of the GOLD trial.  This RCT involved an open-label crossover randomized study design.  The study involved 161 subjects with type 1 diabetes and hemoglobin A1c (HbA1c) of greater than or equal to 7.5% who were treated with multiple daily insulin injections.  All subjects were assigned to receive their initial treatment with a CGIM or standard care for a period of 26 weeks followed by a washout period of 17 weeks and then another 26 weeks with the alternate treatment.  Complete data for analysis was available for a total of 142 subjects (88/2%).  Mean HbA1c was 7.92% during the CIGM phase and 8.35% during the control treatment phase (p<0.001).  Overall mean use time during the CIGM phase was 87.8% (range 86.5-91.9%).  In subjects using the CIGM greater than 70% if the time, HbA1c was reduced by 0.46% compared to no reduction in those using CIGM less than 70% of the time.  Mean self measurement of blood glucose was performed 2.75 times a day in the CIGM group vs. 3.66 times per day in the control group.  The mean percentage of time in a hypoglycemic state (<70 mg/Dl) was 2.97% in the CIGM phase vs. 4.79%  in the control phase.   A second lower hypoglycemic threshold for blood glucose concentration of <54 mg/Dl also reported, with the mean percentage of time  below that threshold reported as 0.79% for the GICM phase vs. 1.89% for the control phase.  Severe hypoglycemic events were reported in one subject in the CIGM phase vs. 5 subjects in the control phase (p=ns).  There were no significant differences between groups with regard to the rate of serious adverse events.  The 19 subjects without full data available were younger, had significantly higher HbA1c and had a history of hypoglycemic events.  The authors made similar conclusions those of the  DIAMOND study:

Among patients with inadequately controlled type 1 diabetes treated with multiple daily insulin injections, the use of continuous glucose monitoring compared with conventional treatment for 26 weeks resulted in lower HbA1c.  Further research is needed to assess clinical outcomes and longer-term adverse effects.

The results from the DIAMOND and GOLD trials are supportive of the use of CIGM in individuals with type 1 diabetes.  However, it should be noted that the benefits were modest, with mean HbA1c reductions between 0,.4 and 0.6% and showed no significant difference between CIGM and standard care with regard to the incidence of severe hypoglycemic events.  Additionally, it must be noted that these study results involved highly motivated and monitored subjects under the care of endocrinologists in the framework of a clinical trial.

Overall, the available RCT evidence addressing the use of CIGM devices in individuals with type 1 diabetes is mixed, but skewed to beneficial outcomes with the use of CIGM devices in individuals with type 1 diabetes.  Data from meta-analyses supports this conclusion, and indicates that the use of CIGM results in improved glycemic control for adults with type 1 diabetes and for children with type 1 diabetes who used real-time CIGM devices.

CIGM use in Individuals with Type 2 Diabetes

Vigersky (2012) and Ehardt (2011) reported the results of an RCT involving 100 subjects with type 2 diabetes not using prandial insulin.  Subjects were assigned to treatment with either intermittent use of a CIGM device for four 2-week cycles (2 weeks on/1 week off, n=50) vs. with SMBG (n=50).  The reported mean decline from baseline in HbA1c in the CIGM vs. the SMBG group was 1.0% vs. 0.5% at 12 weeks post-treatment initiation, 1.2% vs. 0.5% at 24 weeks, 0.8% vs. 0.5% at 38 weeks, and 0.8% vs. 0.2% at 1 year, respectively.  Over the course of the study, the reduction in HbA1c was significantly greater than the SMBG group (p=0.04).  After adjusting for potential confounding variables including age, sex, baseline therapy, and whether the individual started taking insulin during the study, the difference between groups over time remained statistically significant (p<0.001).  It was noted that improvements in the CIGM group occurred without a need for intensification of medical therapy, which was needed in the control group.

Blackberry and others reported the results of a randomized controlled study involving 92 insulin-naive subjects with type 2 diabetes, assigned to either self-monitoring of blood glucose (SMBG; n=42) or SMBG plus short-term CIGM (n=47).  Subjects were prescribed glulisine for subjects with the high post-prandial hyperglycemia excursions.  The authors reported no significant differences between groups with relation to the incidence of major hypoglycemia (p=0.17) or improvements in HbA1c (p=0.31).  However, they did report that more CIGM subjects than SMBG subjects commenced use of glulisine (26/48 vs. 7/44; p<0.001), indicating increased recognition of post-prandial hyperglycemia.

In 2012, the Agency for Healthcare Research and Quality (AHRQ) published a comparative effectiveness review regarding methods of insulin delivery and glucose monitoring.  This review concluded:

We found studies of the comparative effectiveness of rt-CGM versus SMBG only in children, adolescents, and adults with type 1 diabetes.  While prior studies have examined the effect of retrospective CGM in pregnant women with diabetes, no studies have compared rt-CGM with SMBG in this population.  These two glucose monitoring approaches have not been compared in individuals with type 2 diabetes.

A subsequent re-review of this report was conducted and published in a surveillance report in 2016.  The conclusions found no grounds to alter the conclusions regarding CIGM made in the 2012 report.

Overall, the existing evidence addressing the use of CIGM individuals with type 2 diabetes is weaker than that for individuals with type 1 diabetes.  The available meta-analyses report significant variability in the literature with regard to the types of interventions investigated, the frequency of use, and populations involved.  Although the meta-analyses available to date have found a statistically significant benefit of CIGM in terms of glycemic control, the small number of RCTs and the variability among interventions makes it difficult to identify an optimal approach to CIGM use or subgroup of individuals with type 2 diabetes who might benefit.

CIGM use by Pregnant Individuals with Diabetes

In 2013, Voormolen and others published a systematic review of the literature on CIGM during pregnancy.  The review involved 11 studies that met inclusion criteria involving a total of 534 subjects.  Only two of the studies were RCTs.  No meta-analysis was conducted, but they concluded that evidence is limited on the efficacy of CIGM during pregnancy.

The largest RCT published to date investigating the use of CIGM during pregnancy was published by Secher in 2013.  This study involved 154 subjects assigned to either real-time CIGM in addition to routine pregnancy care (n=79) or routine care (n=75).  There were 123 women with type 1 diabetes and 31 with type 2 diabetes included.  The CIGM group used the CIGM device for the 6 days prior to each of 5 study visits, and were encouraged to use the devices continuously.  Subjects in each group were instructed to perform 8 SMBG daily for 6 days before each study visit.  Only 64% of participants in the CIGM group were reported to have complied with the per-protocol use.  No significant differences between groups were noted with regard to HbA1c, SMBG values, insulin dose, and hyper- and hypoglycemic events.  Subjects with type 1 diabetes experienced a significantly greater number of hypoglycemic events vs. type 2 subjects, irrespective of treatment group.  The authors reported 154 pregnancies resulted in 149 live births and 5 miscarriages.  The prevalence of large-for-gestational age infants (at least 90th percentile), the primary study outcome, was 45% in the CIGM group and 34% in the control group, with no difference between groups noted (p=0.19).  No significant differences were reported between groups for the secondary outcome measures, which included prevalence of preterm delivery and the prevalence of severe neonatal hypoglycemia.  Similar findings were reported for type 1 subjects, regardless of treatment group.  The authors noted that the subjects had well-controlled diabetes at baseline, which might help explain the lack of impact of CIGM on outcomes.  Other factors potentially contributing to the negative findings include the intensive SMBG routine in both groups and the relatively low compliance rate (64%) in the CIGM group with the instruction of use the CIGM devices for 6 days before each of 5 study visits.

Murphy (2008) reported the results of an RCT involving 71 pregnant subjects with type 1 (n=46) or type 2 (n=25) diabetes assigned to treatment with either CIGM (n=38) or usual care (n=33).  CIGM group subjects underwent 7 days of CIGM at intervals of 4 to 6 weeks between 8 and 32 weeks of gestation and were advised to measure blood glucose levels at least 7 times a day.  While mean HbA1c levels were lower in the CGIM group at all time-points, these differences were not found to be statistically significant for most measurements.  For the 32-36 week period, the CIGM group had significantly better HbA1c levels vs. controls (p<0.007).  No significant differences were reported between groups with regard to neonatal morbidity or mortality.  Significant differences were noted in favor of the CIGM group with regard to the mean birth weight (p=0.07) and microsomia (p=0.05).  The authors reported that 13/37 (35%) of infants in the CIGM group were large-for gestational age vs. 18 of 30 (60%) in the control group.  The odds ratio for reduced risk of a large-for-gestational age infant with CIGM was 0.36 (95% CI, 0.13 to 0.98; p=0.05).  

While neither of these studies found a statistically significant difference in their primary outcome, and the strength of evidence for the use of CIGM for pregnant individuals is currently weak.  However, such use of CIGM has become the standard of care for this population. 

Major Specialty Medical Society Recommendations

The American Diabetes Association Standards of Medical Care in Diabetes-2016 has recommendations regarding the use of continuous glucose monitoring.  These recommendations state:

The Endocrine Society also has recommendations for the use of CGM devices in their 2016 clinical practice guideline addressing this topic (Peters, 2016):

6. Real-time continuous glucose monitors in adult outpatients6.1 We recommend real-time continuous glucose monitoring (RT-CGM) devices for adult patients with T1DM who have A1C levels above target and who are willing and able to use these devices on a nearly daily basis. (1⊕⊕⊕⊕)
6.2 We recommend RT-CGM devices for adult patients with well-controlled T1DM  who are willing and able to use these devices on a nearly daily basis. (1⊕⊕⊕⊕)

Use of continuous glucose monitoring in adults with type 2 diabetes mellitus
6.3 We suggest short-term, intermittent RT-CGM use in adult patients with T2DM (not on prandial insulin) who have A1C levels 7% and are willing and able to use the device. (2⊕⊕○○)

The Endocrine Society uses the following scheme to grade their recommendations:

      Strength of the recommendation:

Quality of the evidence:

It should be noted that recommendation 6.3 was graded "weak" and based on low quality evidence.

Finally, the American Association of Clinical Endocrinologist (AACE) and the American College of Endocrinology (ACE) produced a consensus statement addressing outpatient glucose monitoring in 2016 (Bailey, 2016).  This document makes the following recommendations for the use of CIGM:

Definitions

Glycemic control:  The ability of an individual's body to control blood glucose concentrations within a specific physiologic range, either on its own or with the assistance of medical therapy.

Hyperglycemia:  A condition characterized by excessively high blood glucose concentrations, generally considered greater than 150 mg/dl.

Hypoglycemia:  A condition characterized by excessively low blood glucose concentrations, generally considered less than 50 mg/dl.

Interstitial glucose:  Glucose present in the fluid present in spaces between the tissue cells of the body.

Type 1 diabetes:  A condition characterized by the impaired or inability of the pancreas to produce insulin. Sometimes known as 'juvenile diabetes.'

Type 2 diabetes:  A condition characterized by a person's body losing the ability to use insulin properly, a problem referred to as insulin resistance.

References

Peer Reviewed Publications:

  1. Beck RW, Riddlesworth T, Ruedy K, et al.; DIAMOND Study Group. Effect of Continuous Glucose Monitoring on Glycemic Control in Adults With Type 1 Diabetes Using Insulin Injections: The DIAMOND Randomized Clinical Trial.
  2. Battelino T, Conget I, Olsen B, et al. The use and efficacy of continuous glucose monitoring in type 1 diabetes treated with insulin pump therapy: a randomised controlled trial. Diabetologia. 2012; 55(12):3155-3162.
  3. Battelino T, Phillip M, Bratina N, et al. Effect of continuous glucose monitoring on hypoglycemia in type 1 diabetes. Diabetes Care. 2011; 34(4):795-800.
  4. Blackberry ID, Furler JS, Ginnivan LE, et al. An exploratory trial of basal and prandial insulin initiation and titration for type 2 diabetes in primary care with adjunct retrospective continuous glucose monitoring: INITIATION study. Diabetes Res Clin Pract. 2014; 106(2):247-255.
  5. Choudhary P, Ramasamy S, Green L, et al. Real-time continuous glucose monitoring significantly reduces severe hypoglycemia in hypoglycemia-unaware patients with type 1 diabetes. Diabetes Care. 2013; 36(12):4160-4162.
  6. Cooke D, Hurel SJ, Casbard A, et al. Randomized controlled trial to assess the impact of continuous glucose  monitoring on HbA1c in insulin-treated diabetes (MITRE Study). Diabet Med. 2009; 26(5):540-547.
  7. Ehrhardt NM, Chellappa M, Walker MS, et al. The effect of real-time continuous glucose monitoring on glycemic control in patients with type 2 diabetes mellitus. J Diabetes Sci Technol. 2011; 5(3):668-675.
  8. Floyd B, Chandra P, Hall S, et al. Comparative analysis of the efficacy of continuous glucose monitoring and self-monitoring of blood glucose in type 1 diabetes mellitus. J Diabetes Sci Technol. 2012; 6(5):1094-1102.
  9. Gandhi GY, Kovalaske M, Kudva Y, et al. Efficacy of continuous glucose monitoring in improved glycemic control and reducing hypoglycemia: a systematic review and meta-analysis of randomized trials. J Diabetes Sci Technol. 2011; 5(4):952-965.
  10. Lind M, Polonsky W, Hirsch IB, et al. Continuous Glucose Monitoring vs Conventional Therapy for Glycemic Control in Adults With Type 1 Diabetes Treated With Multiple Daily Insulin Injections: The GOLD Randomized Clinical Trial. JAMA. 2017; 317(4):379-387.
  11. Juvenile Diabetes Research Foundation Continuous Glucose Monitoring Study Group. Effectiveness of continuous glucose monitoring in a clinical care environment. Diabetes Care. 2010; 33(1):17-22.
  12. Juvenile Diabetes Research Foundation Continuous Glucose Monitoring Study Group. The effect of continuous glucose monitoring in well-controlled type 1 diabetes. Diabetes Care. 2009; 32(8):1378-1383.
  13. Mauras N, Beck R, Xing D, et al. A randomized clinical trial to assess the efficacy and safety of real-time continuous glucose monitoring in the management of type 1 diabetes in young children aged 4 to <10 years. Diabetes Care. 2012; 35(2):204-210.
  14. Murphy HR, Rayman G, Lewis K, et al. Effectiveness of continuous glucose monitoring in pregnant women withdiabetes: randomised clinical trial. BMJ. 2008; 337:a1680.
  15. Newman SP, Cooke D, Casbard A, et al. A randomised controlled trial to compare minimally invasive glucose monitoring devices with conventional monitoring in the management of insulin-treated diabetes mellitus (MITRE). Health Technol Assess. 2009; 13(28):iii-iv, ix-xi, 1-194.
  16. Poolsup N, Suksomboon N, Kyaw AM. Systematic review and meta-analysis of the effectiveness of continuous glucose monitoring (CGM) on glucose control in diabetes. Diabetol Metab Syndr. 2013; 5(1):39.
  17. Raccah D, Sulmont V, Reznik Y, et al. Incremental value of continuous glucose monitoring when starting pump therapy in patients with poorly controlled type 1 diabetes: the RealTrend study. Diabetes Care. 2009; 32(12):2245-2250.
  18. Secher AL, Ringholm L, Andersen HU, et al. The effect of real-time continuous glucose monitoring in pregnant women with diabetes: a randomized controlled trial. Diabetes Care. 2013; 36(7):1877-1883.
  19. Tamborlane WV, Beck RW, Bode BW, et al.; Juvenile Diabetes Research Foundation Continuous Glucose Monitoring Study Group. Continuous glucose monitoring and intensive treatment of type 1 diabetes. N Engl J Med. 2008; 359(14):1464-1476.
  20. Vigersky RA, Fonda SJ, Chellappa M, et al. Short- and long-term effects of real-time continuous glucose monitoring in patients with type 2 diabetes. Diabetes Care. 2012; 35(1):32-38.
  21. Voormolen DN, DeVries JH, Evers IM, et al. The efficacy and effectiveness of continuous glucose monitoring during pregnancy: a systematic review. Obstet Gynecol Surv. 2013; 68(11):753-763.
  22. Yeh HC, Brown TT, Maruthur N, et al. Comparative effectiveness and safety of methods of insulin delivery and glucose monitoring for diabetes mellitus: a systematic review and meta-analysis. Ann Intern Med. 2012; 157(5):336-347.

Government Agency, Medical Society, and Other Authoritative Publications:

  1. Agency for Healthcare Research and Quality (AHRQ). Review: Methods of Insulin Delivery and Glucose Monitoring: Comparative Effectiveness. (2016). Available at: https://effectivehealthcare.ahrq.gov/search-for-guides-reviews-and-reports/?pageaction=displayproduct productID=2182 . Accessed on December 20, 2016.
  2. American Diabetes Association. Standards of Medical Care in Diabetes- 2016. Diabetes Care. 2016; 39(Suppl 4): S1-S112. Available at: http://care.diabetesjournals.org/content/39/Supplement_1. Accessed on December 20, 2016.
  3. Bailey TS, Grunberger G, Bode BW, et al. American Association of Clinical Endocrinologists and American College of Endocrinology 2016 outpatient glucose monitoring consensus statement. Endocr Pract. 2016; 22(2):231-261.
  4. Grunberger G, Bailey T, Camacho PM, et al.; Glucose Monitoring Consensus Conference Writing Committee. Proceedings from the American Association of Clinical Endocrinologists and American College of Endocrinology consensus conference on glucose monitoring. Endocr Pract. 2015; 21(5):522-533. Available at: http://journals.aace.com/doi/pdf/10.4158/EP15653.CS. Accessed on December 20, 2016.
  5. Fonseca VA, Grunberger G, Anhalt H, et al.; Consensus Conference Writing Committee. Continuous glucose monitoring: a consensus conference of the American Association of Clinical Endocrinologists and American College of Endocrinology. Endocr Pract. 2016; 22(8):1008-1021
  6. Handelsman Y, Bloomgarden ZT, Grunberger G, et al. American Association of Clinical Endocrinologists and American College of Endocrinology - clinical practice guidelines for developing a diabetes mellitus comprehensive care plan - 2015. Endocr Pract. 2015; 21(Suppl 1):1-87.
  7. Klonoff DC, Buckingham B, Christiansen JS, et al. Continuous glucose monitoring: an Endocrine Society clinical practice guideline. J Clin Endocrinol Metab. 2011; 96(10):2968-2979.
  8. Langendam M, Luijf YM, Hooft L, et al. Continuous glucose monitoring systems for type 1 diabetes mellitus. Cochrane Database Syst Rev. 2012;(1):CD008101.
  9. Moy FM, Ray A, Buckley BS. Techniques of monitoring blood glucose during pregnancy for women with pre-existing diabetes. Cochrane Database Syst Rev. 2014;(4):CD009613.
  10. Peters AL, Ahmann AJ, Battelino T, et al. Diabetes Technology-Continuous Subcutaneous Insulin Infusion Therapy and Continuous Glucose Monitoring in Adults: An Endocrine Society Clinical Practice Guideline. J Clin Endocrinol Metab. 2016; 101(11):3922-3937.
Websites for Additional Information
  1. American Diabetes Association. Type 1 diabetes. Available at: http://www.diabetes.org/diabetes-basics/type-1/. Accessed on December 20, 2016.
  2. American Diabetes Association. Type 2 diabetes. Available at: http://www.diabetes.org/diabetes-basics/type-2/?loc=db-slabnav/. Accessed on December 20, 2016.
History

Status

Date

Action

  12/27/2017

The document header wording updated from “Current Effective Date” to “Publish Date.” Updated Coding section with 01/01/2018 CPT changes; added code 95249.

  07/01/2017 Updated Coding section with 07/01/2017 HCPCS changes.
Reviewed 02/02/2017 Medical Policy & Technology Assessment Committee (MPTAC) review. Added the terms "professional" and "personal" to the "short term" and "long term" statements. Revised the short-term use criteria from "72 hours" to "6 , 7, or 14 days". Updated Discussion and Reference sections.  
Reviewed 08/04/2016 MPTAC review. Updated Rationale, Discussion and Reference sections.  
Reviewed 05/05/2016 MPTAC review. Updated Discussion and Reference sections.
New 02/04/2016 MPTAC review. Initial document development.