Continuous or Intermittent Monitoring of Glucose in Interstitial Fluid
Durable Medical Equipment
|Original Policy Date
Last Review Status/Date
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The advent of blood glucose monitors for use by patients in the home over 20 years ago revolutionized the management of diabetes. Using fingersticks, patients could monitor their blood glucose level both to determine the adequacy of hyperglycemia control and to evaluate hypoglycemic episodes. Tight diabetic control, defined as a strategy involving frequent glucose checks and a target hemoglobin A1c (HgA1c) in the range of 7%, is now considered standard of care for diabetic patients. Randomized controlled trials (RCTs) of tight control have demonstrated benefits for type I diabetics in decreasing microvascular complications. The impact of tight control on type II diabetic patients and on macrovascular complications such as stroke or myocardial infarction is less certain.
However, tight glucose control requires multiple measurements of blood glucose each day (ie, before meals and at bedtime), a commitment that some patients may be unwilling or unable to meet. In addition, the goal of tight glucose control has to be balanced with an associated risk of hypoglycemia. An additional limitation of periodic self-measurements of blood glucose is that glucose values are seen in isolation, and trends in glucose levels are undetected. For example, while a diabetic patient’s fasting blood glucose level might be within normal values, hyperglycemia might be undetected postprandially, leading to elevated HgA1c values.
Recently, measfurements of glucose in interstitial fluid have been developed as a technique of automatically measuring glucose values throughout the day, producing data that show the trends in glucose measurements, in contrast to the isolated glucose measurements of the traditional blood glucose measurements. Although devices measure glucose in interstitial fluid on a periodic rather than a continuous basis, this type of monitoring is referred to as continuous glucose monitoring (CGM).
Several devices have received U.S. Food and Drug Administration (FDA) approval. The first 2 approved devices were the Continuous Glucose Monitoring System (CGMS®) (MiniMed), which uses an implanted temporary sensor in the subcutaneous tissues, and the GlucoWatch G2® Biographer, an external device worn like a wristwatch that measures glucose in interstitial fluid extracted through the skin with an electric current (referred to as reverse iontophoresis).
Additional devices that have subsequently been approved include those for pediatric use and those with more advanced software, more frequent measurements of glucose levels, more sophisticated alarm systems, etc. Devices initially measured interstitial glucose every 5 to 10 minutes and, with currently available devices the time intervals at which interstitial glucose is measured ranges from every 1 to 2 minutes to 5 minutes. While CGMs potentially eliminate or decrease the number of required daily fingersticks, it should be noted that, according to the FDA labeling, monitors are not intended to be an alternative to traditional self-monitoring of blood glucose levels but rather provide adjunct monitoring, supplying additional information on glucose trends that are not available from self-monitoring. In addition, it is important to note that devices may be used intermittently, eg, time periods of 72 hours, or on a long-term basis.
In addition to stand-alone CGMs, several insulin pump systems have included a built-in CGM. This policy addresses continuous glucose monitoring devices, not the insulin pump portion of these systems.
Several continuous glucose monitoring systems have been approved by FDA through the premarket approval process:
- The Continuous Glucose Monitoring System (CGMS®) (MiniMed) in 1999 (approved for 3-day use in a physician's office).
- The GlucoWatch G2® Biographer in 2001. Of note, neither the GlucoWatch nor the autosensors have been available after July 31, 2008.
- The Guardian®-RT (Real-Time) CGMS (Medtronic, MiniMed) in July 2005. (MiniMed was purchased by Medtronic).
- The DexCom® STS CGMS system (DexCom) was approved by FDA in March 2006.
- The Paradigm® REAL-Time System (Medtronic, MiniMed) was approved by FDA in 2006. This system integrates a CGM with a Paradigm insulin pump. The second generation integrated system is called the MiniMed Paradigm Revel System.
- The FreeStyle Navigator® CGM System (Abbott) was approved in March 2008.
- The DexCom G4 Platinum (DexCom) CGM was approved for use in adults 18 years and older in October 2012. The device can be worn for up to 7 days. In February 2014, FDA expanded use of the Dexcom Platinum CGM to include patients with diabetes, age 2 to 17 years-old.
Intermittent monitoring, ie, 72 hours, of glucose levels in interstitial fluid may be considered medically necessary in patients with type 1 diabetes mellitus whose diabetes is poorly controlled, despite current use of best practices (see Policy Guidelines section). Poorly controlled type 1 diabetes mellitus includes the following clinical situations: unexplained hypoglycemic episodes, hypoglycemic unawareness, suspected postprandial hyperglycemia, and recurrent diabetic ketoacidosis.
Intermittent monitoring of glucose levels in interstitial fluid may also be considered medically necessary in patients with type I diabetes prior to insulin pump initiation to determine basal insulin levels.
Continuous, ie, long-term, monitoring of glucose levels in interstitial fluid, including real-time monitoring, as a technique of diabetic monitoring, may be considered medically necessary when the following situations occur, despite use of best practices:
Patients with type I diabetes who have recurrent, unexplained, severe (generally blood glucose levels less than 50 mg/dL) hypoglycemia for whom hypoglycemia puts the patient or others at risk;
or patients with type I diabetes who are pregnant whose diabetes is poorly controlled. Poorly controlled type I diabetes includes unexplained hypoglycemic episodes, hypoglycemic unawareness, suspected postprandial hyperglycemia, and recurrent diabetic ketoacidosis.
Other uses of continuous monitoring of glucose levels in interstitial fluid as a technique of diabetic monitoring are considered investigational.
Several insulin pump systems (eg, Omnipod Insulin Management System, Paradigm REAL-Time System) have a built-in continuous glucose monitor (CGM). This policy is evaluating the CGM-device only; the policy does not evaluate insulin pumps. In the case of insulin pumps systems with a built-in CGM and a low glucose suspend (LGS) feature, the CGM device and the low glucose suspend feature are evaluated in the policy, not the insulin pump.
Best practices in diabetes control for patients with diabetes mellitus include compliance with a regimen of 4 or more fingersticks each day and use of an insulin pump. During pregnancy, 3 or more insulin injections daily could also be considered best practice for patients not on an insulin pump prior to the pregnancy. Prior use of an intermittent (72-hour) glucose monitor would be considered a part of best practices for those considering use of a continuous glucose monitor.
Women with type 1 diabetes mellitus taking insulin who are pregnant or about to become pregnant with poorly controlled diabetes are another subset of patients to whom the policy statement on intermittent monitoring may apply.
Intermittent monitoring is generally conducted in 72-hour periods. It may be repeated at a subsequent time depending on the patient’s level of diabetes control.
The strongest evidence exists for use of CGM devices in patients age 25 and older. However, age may be a proxy for motivation and good control of disease, so it is also reasonable to select patients based on their ability to self-manage their disease, rather than age.
In 2009, the language of the CPT codes that specifically describe monitoring of glucose levels in the interstitial fluid using implanted devices was revised to state that the devices are used for a minimum of 72 hours:
95250: Ambulatory continuous glucose monitoring of interstitial tissue fluid via a subcutaneous sensor for a minimum of 72 hours; hook-up, calibration of monitor, patient training, removal of sensor, and printout of recording
95251 ;interpretation and report
CPT code 99091 might also be used for this monitoring:
99091: Collection and interpretation of physiologic data (e.g., ECG, blood pressure, glucose monitoring) digitally stored and/or transmitted by the patient and/or caregiver to the physician or other qualified healthcare professional, requiring a minimum of 30 minutes of time.
For 2008, HCPCS codes were added specifically for continuous glucose monitoring systems:
A9276 Sensor; invasive (e.g., subcutaneous), disposable, for use with interstitial continuous glucose monitoring system, one 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
BlueCard/National Account Issues
State or federal mandates (e.g., FEP) may dictate that all devices approved by the U.S. Food and Drug Administration (FDA) may not be considered investigational. Therefore, FDA-approved devices may be assessed on the basis of their medical necessity.
State mandates regarding coverage of diabetic supplies may apply; however, some state mandates may only apply to those supplies that are no longer considered investigational.
This policy was originally created in 2000 and was updated regularly with searches of the MEDLINE database. A TEC Assessment was published in 2003.(1) The most recent literature review was performed through November 11, 2014. Following is a summary of the key literature to date.
Continuous glucose monitoring systems
Most of the following discussion focuses on the clinical utility of continuous glucose monitoring (CGM) systems. That is, their ability to provide either additional information on glucose levels, leading to improved glucose control or to improve the morbidity/mortality associated with clinically significant severe and acute hypoglycemic or hyperglycemic events. Because diabetic control encompasses numerous variables including the diabetic regimen and patient self-management, randomized controlled trials (RCTs) are important to isolate the contribution of interstitial glucose measurements to the overall diabetic management. Data on patients with type 1 diabetes and type 2 diabetes are discussed separately.
Type 1 diabetes
Several meta-analyses of RCTs have been published; they have focused on slightly different populations eg, age and/or type of diabetes, and different study designs, eg, by length of follow-up. Two 2011 meta-analyses included studies on adults and/or children. The study by Gandhi et al identified studies conducted among patients with type 1 and/or type 2 diabetes and stratified findings by type of diabetes. (2) The investigators identified 19 RCTs evaluating CGM interventions lasting at least 8 weeks and conducted in the outpatient setting. Mean baseline hemoglobin A1c (HbA1c) was at least 7.0% in all studies but included 1 in which the mean baseline HbA1c was 6.4%. Overall, compared with self-monitoring of blood glucose, CGM 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.
Another 2011 meta-analysis of RCTs on CGM included trials conducted in adults and children with type 1 diabetes who were on an intensive insulin regimen (studies of type 2 diabetes were not included).(3) This meta-analysis required a minimum of 12 weeks of follow-up in the studies (as compared with at least 8 weeks in the Gandhi meta-analysis). Studies compared CGM with self-monitored blood glucose (SMBG); there was no restriction related to type of CGM device, but the CGM readings had to be used to adjust insulin dose or modify diet. A total of 14 RCTs met eligibility criteria. In a pooled analysis, there was a statistically significant reduction in HbA1c with CGM compared with SMBG (WMD= -0.26%; 95% CI, -0.34% to -0.19%). In a subgroup analysis by age, there were significant reductions in HbA1c with CGM in studies of adults (n=5) (WMD= -0.33; 95% CI, -0.46 to -0.20) and in studies with children and/or adolescents (n=8) (WMD= -0.25; 95% CI, -0.43 to -0.08).
Two 2012 meta-analyses evaluating the efficacy of CGM in patients with type 1 diabetes had similar findings: overall, use of CGM to result in significantly greater reductions in HbA1c compared with SMBG.(4,5) Most recently, a 2013 systematic review by Poolsup et al included RCTs that compared CGM with SMBG, had interventions lasting at last 8 weeks, and reported HbA1c as an outcome.(6) For type 1 diabetes, only studies in children were included. Ten RCTs including pediatric patients with type 1 diabetes met inclusion criteria and were included in a meta-analysis. Overall, the investigators did not find that CGM had a significantly greater impact on HbA1c than 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 by approach to CGM, devices that provided data retrospectively (retrospective CGM) did not result in better glucose control than SMBG (5 studies; pooled mean difference, -0.05%; 95% CI, 0.46% to 0.35%). However, real-time CGM was superior to SMBG in terms of improving glycemic control (5 studies; pooled mean difference, 0.18%; 95% CI, 0.35% to 0.02%).
Representative RCTs follow:
In 2008, the Juvenile Diabetes Research Foundation (JDRF) published results of a study that randomly assigned 322 adults and children with type I diabetes to CGM or self-(home) monitoring.(7) With HbA1c as the primary outcome measure, there was a significant difference among patients 25 years of age or older that favored continuous monitoring (mean HbA1c difference, 0.53%), while the difference between groups was not statistically significant for those ages 15 to 24 years or 8 to 14 years. The population in this study had relatively well-controlled diabetes in that entry criterion was glycated Hb of 7% to 10%, but approximately 70% had levels between 7% and 8%; in addition, more than 70% of patients were using an insulin pump. No significant differences were noted in rates of hypoglycemic events, but the study was likely not sufficiently large to detect potential differences. The authors also reported that monitor use was greatest in those patients ages 25 or older, the group in which 83% of patients used the monitor 6 or more days per week. The investigators also conducted a nonblinded single-arm 6-month extension to the randomized trial in which patients in the control group were offered a CGM device.(8) A total of 214 of 219 (98%) in the control group participated in the extension. This included 80 (37%) who were at least 25 years old, 73 (34%) who were 15 to 24-years old, and 61 (29%) who were 8 to 14-years old. The mean HbA1c level at the time of initiation of CGM use was 7.4%±0.7%. Patients were instructed to use the device on a daily basis. Among the 154 patients with baseline A1c at least 7%, there was a significant decrease in A1c 6 months after initiating device use in the older age group (mean change in A1c, -0.4%±0.5%; p<0.001). HbA1c did not decrease significantly in the 15 to 24-year olds (0.01%±0.7%, p=0.95) or in the 8 to 14-year olds (0.02±0.7%, p=0.85). Greater decrease in HbA1c was associated with more frequent use of the CGM device (p=0.001, adjusted for age group). Frequency of device use tended to decrease over time, with less of a decrease in the older age group. At month 6, median use of CGM devices was 6.5 days per week among the older age group, 3.3 days among the 15 to 24-year olds, and 3.7 days per week among the children. During the 6-month extension, the rate of severe hypoglycemic events was 15 per 100 person-years of follow-up.
An additional randomized trial by the JDRD, published in 2009, studied the potential benefits of CGM in the management of adults and children with well-controlled type 1 diabetes.(9) In this study, 129 adults and children with intensively treated type 1 diabetes (age range, 8-69 years) and HbA1c less than 7.0% were randomly assigned to either continuous or standard glucose monitoring for 26 weeks. The main study outcomes were time with glucose level at or below 70 mg/dL, HbA1c level, and severe hypoglycemic events. At 26 weeks, biochemical hypoglycemia (≤70 mg/dL) was less frequent in the CGM group than in the control group (median 54 vs 91 min/d, respectively), but the difference was not statistically significant (p=0.16). Time out of range (≤70 or >180 mg/dL) was significantly lower in the CGM group than in the control group (377 vs 491 min/d, respectively, p=0.003).There was a significant treatment group difference favoring the CGM group in mean HbA1c at 26 weeks adjusted for baseline values. One or more severe hypoglycemic events occurred in 10% and 11% of the 2 groups, respectively (p not significant). The authors concluded that the weight of evidence suggests that CGM is beneficial for individuals with type 1 diabetes who have already achieved excellent control with HbA1c of less than 7.0%. This is a relatively small study. In addition, the clinical significance of some of these findings is not certain. Some of the patients in this group would likely meet policy statements for use of CGM.
The MITRE trial, published by Newman et al in 2009, was conducted to evaluate whether the additional information provided by use of minimally invasive glucose monitors resulted in improved glucose control in patients with poorly controlled insulin-requiring diabetes.(10) This was a 4-arm RCT conducted at secondary care diabetes clinics in 4 hospitals in England. In this study, 404 people aged older than 18 years, with insulin-treated diabetes mellitus (types 1 or 2) for at least 6 months, who were receiving 2 or more injections of insulin daily, were eligible. Most participants, 57%, had type 1 diabetes, 41% had type 2 diabetes, and 2% were classified as “other.” Participants had 2 HbA1c values of at least 7.5% in the 15 months prior to entry and were randomized to 1 of 4 groups. Two groups received minimally invasive glucose monitoring devices (GlucoWatch Biographer or MiniMed Continuous Glucose Monitoring System, CGMS). Intermittent CGM was used ie, monitoring was performed over several days at various points in the study. These groups were compared with an attention control group (standard treatment with nurse feedback sessions at the same frequency as those in the device groups) and a standard control group (reflecting common practice in the clinical management of diabetes). Change in HbA1c from baseline to 3, 6, 12, and 18 months was the primary indicator of short- to long-term efficacy in this study. At 18 months, all groups demonstrated a decline in HbA1c levels from baseline. Mean percentage changes in HbA1c were -1.4 for the GlucoWatch group, -4.2 for the CGMS group, -5.1 for the attention control group, and -4.9 for the standard care control group. In the intention-to-treat (ITT) analysis, no significant differences were found between any of the groups at any of the assessment times. There was no evidence that the additional information provided by the devices resulted in any change in the number or nature of treatment recommendations offered by the nurses. Use and acceptability indicated a decline in use of both devices, which was most marked in the GlucoWatch group by 18 months (20% still using GlucoWatch vs 57% still using the CGMS). In this study of unselected patients, use of CGMs (CGMS on an intermittent basis) did not lead to improved clinical outcomes.
In 2011, Mauras et al published an analysis from the Diabetes Research in Children Network (DirecNet) Study Group that evaluated CGM in the management of young children aged 4 to less than 10 years with type 1 diabetes.(11) A total of 146 children (mean age, 7.5 years) were randomized to CGM or usual care. At baseline, 30 children (42%) had an HbA1c of at least 8%. The primary outcome was clinical success as defined as reduction in HbA1c by at least 0.5% without the occurrence of severe hypoglycemia at 26 weeks. Clinical success was attained by 19% in the CGM group and 28% in the usual care group (p=0.17). Mean change in HbA1c, a secondary outcome, did not differ significantly between groups (-0.1 in each group, p=0.79).
There are numerous RCTs and several systematic reviews of RCTs evaluating CGM in patients with type 1 diabetes. Systematic reviews generally found that CGM use resulted in improved glycemic control for adults with type 1 diabetes and for children with type 1 diabetes who used real-time CGM devices.
Type 2 diabetes
Two of the systematic reviews previously described in the section on type 1 diabetes also reported on the efficacy of CGM in patients with type 2 diabetes. Gandhi et al(2) identified 3 RCTs that included patients with type 2 diabetes (one of these included patients with either type of diabetes). There was a mixture of patients with type 2 diabetes who did and did not require insulin. In a meta-analysis of the 3 trials, there was a statistically significant reduction in HbA1c with CGM compared with SMBG in adults with type 2 diabetes (WMD= -0.70; 95% CI, -1.14 to -0.27). In 2013, Poolsup et al(6) conducted a meta-analysis of 4 trials conducted with adults with type 2 diabetes. In a pooled analysis, CGM had greater efficacy in terms of HbA1c than usual care. The pooled mean difference in HbA1c was -0.31% (95% CI, -0.6 to 0.02, p=0.04). Because of a lack of statistical heterogeneity among studies, subgroup analyses (eg, by type of CGM device) were not performed. However, there were some differences among studies; one used retrospective CGM and 2 used real-time CGM. Also, there was variability in the frequency of CGM use, making it difficult to determine the optimal frequency of use.
A representative study included in the 2013 meta-analysis evaluated intermittent use of a CGM device in 100 patients with type 2 diabetes who did not use prandial insulin.(12,13) Eligible participants were 18 or older, had type 2 diabetes for at least 3 months, and had an initial HbA1c of at least 7% but not more than 12%. The study compared real-time continuous monitoring with the DexCom device used for four 2-week cycles (2 weeks on/1 week off) with SMBG. The primary efficacy outcome was mean change in HbA1c. The mean decline from baseline in HbA1c in the CGM versus the SMBG group was 1.0% versus 0.5% at 12 weeks, 1.2% versus 0.5% at 24 weeks, 0.8% versus 0.5% at 38 weeks, and 0.8% versus 0.2% at 1 year, respectively. Over the course of the study, the reduction in HbA1c was significantly greater than in 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).
There are fewer RCTs on CGM in patients with type 2 diabetes than for patients with type 1 diabetes. Systematic reviews that included 3 to 4 RCTs found that there was variability in the intervention, eg, type of CGM device, frequency of use and patient populations eg, adults and/or children. Although systematic reviews have found a statistically significant benefit of CGM in terms of glycemic control, the small number of RCTs and variability among interventions makes it difficult to identify an optimal approach to CGM use or subgroup of type 2 diabetes patients who might benefit.
Pregnant women with diabetes
In 2013, Voormolen et al published a systematic review of the literature on CGM during pregnancy.(14) The authors identified 11 relevant studies (ie, published in peer-review journals and evaluating the utility of CGM in pregnancy). Two of the studies were RCTs. The 11 studies included a total of 534 women; the largest study was an RCT that had 154 participants. Seven of the studies used retrospective CGM, and the remaining 4 studies used real-time CGM. The authors did not pool study findings; they concluded that evidence is limited on the efficacy of CGM during pregnancy. The 2 published RCTs are described next:
The larger RCT was published by in 2013 by Secher et al in Denmark.(15) The investigators randomized 154 women to real-time CGM in addition to routine pregnancy care (n=79) or routine pregnancy care alone (n=75). There were 123 women with type 1 diabetes and 31 with type 2 diabetes. Patients in the CGM group were instructed to use the CGM device for 6 days before each of 5 study visits and were encouraged to use the devices continuously. Participants in both groups were instructed to perform 8 daily self-monitored plasma glucose measurements for 6 days before each visit. Baseline mean HbA1c was 6.6% in the CGM group and 6.8% in the routine care group. The 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 CGM group and 34% in the routine care group. The difference between groups was not statistically significant (p=0.19). In addition, no statistically significant differences were found between groups for secondary outcomes, including the prevalence of preterm delivery and the prevalence of severe neonatal hypoglycemia. Women in this study had low baseline HbA1c, which might help explain the lack of impact of CGM 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 CGM group with the instruction of use the CGM devices for 6 days before each of 5 study visits.
In 2008, Murphy et al in the U.K. randomized 71 pregnant women with type 1 (n=46) or type 2 (n=25) diabetes to CGM or usual care.(16) The intervention consisted of up to 7 days of CGM at intervals of 4 to 6 weeks between 8 and 32 weeks’ gestation. In addition to CGM, the women were advised to measure blood glucose levels at least 7 times a day. Baseline HbA1c was 7.2% (SD=0.9) in the CGM group and 7.4% (SD=1.5) in the usual care group. The primary study outcome was maternal glycemic control during the second and third trimesters. Mean HbA1c levels were consistently lower in the intervention arm, but differences between groups were not statistically significant at any time point. For example, between 28 and 32 weeks’ gestation, mean HbA1c levels were 6.1% (SD=0.60) in the CGM group and 6.4% (SD=0.8) in the usual care group (p=0.10). The prevalence of large-for-gestational age infants (at least 90th percentile) was a secondary outcome. Thirteen of 37 (35%) infants in the CGM group were large-for-gestational age compared with 18 of 30 (60%) in the usual care group. The odds ratio for reduced risk of a large-for-gestational age infant with CGM was 0.36 (95% CI, 0.13 to 0.98; p=0.05).
Neither RCT found a statistically significant difference in their primary outcome. The Murphy study found a borderline statistically significantly lower rate of large-for-gestational age infants in women who used CGM while pregnant. Taken together, 2 published RCTs on CGM in pregnancy do not provide strong evidence that routine CGM during pregnancy is beneficial. However, it is difficult to draw definitive conclusions from this limited evidence.
Other diabetic subgroups
CGM has been proposed for specific diabetic subgroups such as patients with poor diabetic control, as evidenced by recurrent hypoglycemia, hypoglycemia unawareness, postprandial hyperglycemia, and/or recurrent diabetic ketoacidosis. For these groups, CGM provides different types of information than single glucose measurements, such as trends in glucose and rates of change. There is only anecdotal evidence for the efficacy of this approach; there is no high-quality evidence available to evaluate the impact of this approach on health outcomes.
Continuous glucose monitoring systems integrated with an insulin pump
Recent advances in technology now allow linkage between the CGM device and an insulin pump. In a randomized study of 132 adults and children from France reported in 2009, Raccah et al reported improved HbA1c levels (change in A1c of 0.96% vs 0.55%, respectively) in patients who were fully protocol compliant for use of an insulin pump integrated with CGMS compared with those using a pump with standard glucose self-monitoring.(17) In 2012, Battelino et al published findings of a multicenter crossover study conducted in several European countries that included 153 children and adults with type 1 diabetes.(18) The study used the MiniMed Paradigm REAL-Time system, which integrates a CGM device and an insulin pump system. Patients were randomized to use of the system for 6 months with the sensor on and 6 months with the sensor off, in random order, with a washout period of 4 months between interventions. Baseline HbA1c ranged from 7.5% to 9.5%. After treatment, mean HbA1c was 8.04% in the sensor on arm and 8.47% in the sensor off arm. The mean difference in HbA1c between groups was -0.43% (95% CI, -0.32% to -0.55%; p<0.001). Neither of the above trials was blinded, and neither compared continuous with intermittent use of the CGM.
Clinical Input Received Through Physician Specialty Societies and Academic Medical Centers
While the various physician specialty societies and academic medical centers may collaborate with and make recommendations during this process, through the provision of appropriate reviewers, input received does not represent an endorsement or position statement by the physician specialty societies or academic medical centers, unless otherwise noted. In response to requests, input was received from 1 physician specialty society and 4 academic medical centers. Those providing input concurred that this
technique, particularly intermittent glucose monitoring, was helpful in a subset of patients with diabetes. Reviewers commented that this monitoring can improve diabetes care by reducing glucose levels (and improving HbA1c) and/or by reducing episodes of hypoglycemia. Reviewers believed that there was persuasive information from case reports to demonstrate the positive impact of intermittent glucose monitoring.
Summary of Evidence
The available studies demonstrate that glucose monitoring may improve glucose control in type I diabetic patients. However, the data on the impact of long-term continuous glucose monitoring are still limited. Studies such as that of the Juvenile Diabetes Research Foundation (JDRF) suggest that more frequent use of continuous glucose monitors (CGMs) may result in better outcomes, but this finding is not consistent across all available studies. In addition, the magnitude of effect is modest, suggesting that either the efficacy is of a small magnitude or that only a subset of patients benefit from this type of monitoring. Thus, the impact of CGM use on glucose control for the general diabetic population is uncertain, and CGM is considered investigational for the purpose of improving glucose control in the general diabetic population.
CGM provides more data points on glucose levels, and also provides information about trends. This additional information is most likely to benefit subgroups of diabetic patients, ie, those patients with type I diabetes who do not have adequate control, including episodes of hypoglycemia, despite use of current best practices including multiple (≥4) daily checks of blood glucose and use of an insulin pump. Based on the available data and supported by strong clinical input, intermittent, ie, 72-hour, glucose monitoring may be considered medically necessary in those whose type 1 diabetes is poorly controlled, despite use of best practices.
Using a rationale similar to that just noted for intermittent monitoring, continuous monitoring can also be used in diabetic subpopulations. Continuous glucose monitoring may be considered medically necessary to provide additional data for management of those who have recurrent, unexplained, severe hypoglycemia that puts the patient or others at risk, despite use of current best practices, and also for pregnant patients with type I diabetes.
The available literature suggests that CGM systems may improve glycemic control in patients with type 2 diabetes but too few studies have focused on this population, and it is not clear what subset of patients with type 2 diabetes might benefit from intermittent or continuous glucose monitoring. Due to the limited evidence, use of CGM systems in patients with type 2 diabetes is considered investigational.
Practice Guidelines and Position Statements
In 2013, the American Diabetes Association made the following recommendations concerning continuous glucose monitoring(19):
- CGM in conjunction with intensive insulin regimens can be a useful tool to lower A1c in selected adults (age at least 25 years) with type 1 diabetes. (Level of evidence A)
- Although the evidence of A1c lowering is less strong in children, teens, and younger adults, CGM may be helpful in those groups. Success correlates with adherence to ongoing use of the device. (Level of evidence C)
- CGM may be a supplemental tool to SMBG [self-monitoring of blood glucose] in those with hypoglycemic unawareness and/or frequent hypoglycemic episodes. (Level of evidence E)
In 2011, the Endocrine Society published a clinical practice guideline developed by a task force that included the following recommendations on continuous glucose monitoring(20):
- 1.0 Real-time continuous glucose monitoring (RT-CGM) in adult hospital settings
- We recommend against the use of RT-CGM alone for glucose management in the intensive care unit or operating room until further studies provide sufficient evidence for its accuracy and safety in those settings.
- Children and adolescent outpatients
- We recommend that RT-CGM with currently approved devices be used by children and adolescents with type 1 diabetes mellitus who have achieved HbA1c levels below 7.0%.
- We recommend RT-CGM devices be used with children and adolescents with type 1 diabetes who have HbA1c levels 7.0% or higher who are able to use these devices on a nearly daily basis.
- We make no recommendations for or against the use of RT-CGM by children with type 1 diabetes who are less than 8 yr of age.
- We suggest that treatment guidelines regarding use of RT-CGM be provided to patients.
- We suggest the intermittent use of CGM systems designed for short-term retrospective analysis in pediatric patients with diabetes in whom clinicians worry about nocturnal hypoglycemia, dawn phenomenon, and postprandial hyperglycemia; in patients with hypoglycemic unawareness; and in patients experimenting with important changes to their diabetes regimen.
- Adult outpatients
- We recommend that RT-CGM devices be used by adult patients with type 1 diabetes who have HbA1c levels of at least 7.0% and who have demonstrated that they can use these devices on a nearly daily basis.
- We recommend that RT-CGM devices be used by adult patients with type 1 diabetes who have HbA1c levels less than 7.0% and who have demonstrated that they can use these devices on a nearly daily basis.
- We suggest that intermittent use of CGM systems designed for short-term retrospective analysis may be of benefit in adult patients with diabetes to detect nocturnal hypoglycemia, the dawn phenomenon, and postprandial hyperglycemia, and to assist in the management of hypoglycemic unawareness and when significant changes are made to their diabetes regimen.
US Preventive Services Task Force Recommendations
The US Preventive Services Task Force has not addressed continuous or intermittent glucose monitoring in patients with diabetes.
Medicare National Coverage
A 2006 National Coverage Determination (NCD) states that home blood glucose monitors are covered for patients meeting the following criteria:
- The patient has been diagnosed with diabetes;
- The patient’s physician states that the patient is capable of using the device appropriately; and
- The device is designed for home use.
The NCD did not specifically mention continuous versus intermittent use of home blood glucose monitors.
- Blue Cross and Blue Shield Technology Evaluation Center (TEC). Use of Intermittent or Continuous Interstitial Fluid Glucose Monitoring in Patients with Diabetes Mellitus. TEC Assessments. 2003;Volume 18, Tab 16.
- 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.
- Wojciechowski P, Rys P, Lipowska A, et al. Efficacy and safety comparison of continuous glucose monitoringand self-monitoring of blood glucose in type 1 diabetes. Pol Arch Med Wewn. 2011;121(10):333-343.
- Langendam M, Luijf YM, Hooft L, et al. Continuous glucose monitoring systems for type 1 diabetes mellitus. Cochrane Database Syst Rev. 2012;1:CD008101. PMID 22258980
- Floyd B, Chandra P, Hall S, et al. Comparative analysis of the efficacy of continuous glucose monitoring and selfmonitoring of blood glucose in type 1 diabetes mellitus. J Diabetes Sci Technol. Sep 2012;6(5):1094-1102. PMID 23063035
- 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. Jul 23 2013;5(1):39. PMID 23876067
- 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):1469-1476.
- 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.
- 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.
- 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, 1-194.
- 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.
- 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.
- 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.
- Voormolen DN, Devries JH, Evers IM, et al. The efficacy and effectiveness of continuous glucose monitoring during pregnancy: a systematic review. Obstet Gynecol Surv. Nov 2013;68(11):753-763. PMID 24193194
- 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. Jan 24 2013. PMID 23349548
- Murphy HR, Rayman G, Lewis K, et al. Effectiveness of continuous glucose monitoring in pregnant women with diabetes: randomised clinical trial. BMJ. 2008;337:a1680. PMID 18818254
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- 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. Dec 2012;55(12):3155-3162.PMID 22965294
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- 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.
|CPT||95250||Ambulatory glucose monitoring of interstitial tissue fluid via a subcutaneous sensor for up to 72 hours;sensor placement, hook-up, calibration of monitor, patient training, removal of sensor, and printout of recording|
|95251||; physician interpretation and report|
|ICD-9 Diagnosis||250.00 – 250.93||Diabetes mellitus range of codes|
|HCPCS||A9276||Sensor; invasive (e.g., subcutaneous), disposable, for use with interstitial continuous glucose monitoring system, one 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|
|S1030||Continuous non-invasive glucose monitoring device, purchase (for physician interpretation of data, use CPT code)|
|S1031||Continuous non-invasive glucose monitoring device, rental, including sensor, sensor replacement, and download to monitor (for physician interpretation of data, use CPT code)|
|ICD-10-CM (effective 10/1/15)||E10.10-E13.9||Diabetes mellitus code range|
|ICD-10-PCS (effecitve 10/1/15)||ICD-10-PCS codes are only used for inpatient services. There is no specific ICD-10-PCS code for this monitoring.|
|Type of Service||Medicine|
|Place of Service||Outpatient|
Continuous Glucose Monitoring
Glucose Monitoring, Continuous
GlucoWatch, Glucose Monitoring
MiniMed, Glucose Monitoring
|08/18/00||Add to Durable Medicine section||New policy|
|12/15/00||Replace policy||Benefits application section revised to include information regarding BlueCard or National Account|
|05/15/02||Replace policy||Policy reviewed; policy state unchanged; reference to 2002 TEC Assessment included|
|12/18/02||Replace policy||Policy updated to include FDA approval for Glucowatch in children; policy statement unchanged|
|12/17/03||Replace policy||Policy updated focusing on randomized trials of Glucowatch and CGMS devices; policy statement unchanged|
|07/15/04||Replace policy||Updated specifications for the GlucoWatch G2 Biographer added|
|11/09/04||Replace policy||Literature review update for the period of October 2003 through August 2004; information on the Guardian CGMS added. Policy statement unchanged|
|09/27/05||Replace policy||Literature review update for the period of August 2004 through June 2005; reference number 12 added. Policy statement unchanged|
|02/15/07||Replace policy||Policy updated with literature review from June 2005 through December 2006. Information about real-time continuous monitoring added to description section. Policy statement changed to indicated that real-time continuous monitoring is also investigational. Reference numbers 1, 2, 15–19 added|
|04/09/08||Replace Policy||Policy updated with literature review. Reference numbers 20-25 added|
|08/14/08||Replace policy||Policy updated with literature review; reference numbers 26, 28, and 29 added. Clinical input reviewed.|
|12/01/08||Replace policy||Policy updated with literature review; reference numbers 26, 28, and 29 added. Clinical input reviewed. New policy statement added that intermittent (72 hours) glucose monitoring may be considered medically necessary when specific criteria are met; continuous (long-term) monitoring also may be considered medically necessary when specific, but different, criteria are met.|
|03/11/10||Replace policy||Policy updated with literature review, reference numbers 31-34 added; policy statements unchanged|
|3/10/11||Replace policy||Policy updated with literature review. Rationale extensively rewritten. References 14,16,19,20,23 and 24 added; other references renumbered or removed. Policy statements unchanged.|
|03/08/12||Replace policy||Policy updated with literature review. References 3, 4, 9-11, 15-17 and 19 added; other references renumbered or removed. Policy statements unchanged.|
|03/14/13||Replace policy||Policy updated with literature review through February 6, 2013. Policy statement added that artificial pancreases are considered investigational. The word “symptomatic” removed from third policy statement. References 5, 6, 14, 15, 17-20 added; other references renumbered or removed.|
|3/13/14||Replace policy||Policy updated with literature review through February 3, 2014. References 6, 14, 16, 19, 20, and 23-27 added; other references renumbered or removed. Policy statements unchanged.|
|7/1/14||Replace policy- coding update only||added new HCPCS codes S1034-S1037|
|12/11/14||Replace policy||Policy updated with literature review through November 11, 2014. Material on artificial pancreas device systems, including the policy statement, removed from policy. Other policy statements unchanged. OmniPod removed from policy as it does not have a CGM included.|