Continuous or Intermittent Monitoring of Glucose in Interstitial Fluid

Medical Policy: 01.01.03 
Original Effective Date: May 2000 
Reviewed: May 2011 
Revised: September 2009 

Benefit Application
Benefit determinations are based on the applicable contract language in effect at the time the services were rendered. Exclusions, limitations or exceptions may apply. Benefits may vary based on contract, and individual member benefits must be verified. Wellmark determines medical necessity only if the benefit exists and no contract exclusions are applicable. This medical policy may not apply to FEP. Benefits are determined by the Federal Employee Program.

This Medical Policy document describes the status of medical technology at the time the document was developed. Since that time, new technology may have emerged or new medical literature may have been published. This Medical Policy will be reviewed regularly and be updated as scientific and medical literature becomes available.

Description: 

The use of blood glucose monitors in the home has greatly impacted the management of diabetes. Several clinical trials have demonstrated that decreases in diabetes complications are associated with tight glucose control, defined as HbA1c measurement of less than 7%.

Recently, measurements of glucose obtained from the interstitial fluid have been utilized as a technique for automatically measuring glucose values throughout the day. Although the time interval at which interstitial glucose is measured ranges from every 5 to 10 minutes, all such monitoring devices are commonly referred to as continuous glucose monitors.

These devices do not eliminate the need for finger stick blood glucose measurements. Two to four times a day calibration must be done with finger stick blood glucose readings and each interstitial fluid glucose reading must be validated by finger stick blood glucose readings before any adjustments in insulin or other interventions are made. This is true even if the device is associated with an insulin pump.

Examples of these devices include;

• The Continuous Glucose Monitoring System (CGMS) (MiniMed) and the upgraded version, the Guardian CGMS, consist of a subcutaneously inserted sensor that is attached to a small plastic disk the size of a dime and is taped to the skin to hold the sensor in place. A thin wire connects the sensor to a pager-sized glucose monitor, which records and stores glucose values in memory. An electrical signal is continuously relayed to the glucose sensor, which records glucose levels every 5 minutes, some 288 values per day. For calibration purposes, the manufacturer recommends that the patient enter the results of 4 finger stick blood glucose measurements per day into the monitor. For the Guardian CGMS, it is recommended that the device be calibrated with finger stick blood glucose levels every 12 hours at a minimum. The CGMS sensors are capable of transmitting values for up to 3 days, after which time the sensor must be removed and replaced with another by the patient, if additional monitoring is needed. The Guardian CGMS can store up to 21 days of data. The data captured in the monitor can be downloaded to a personal computer for review and used by a physician or the patient. Unlike the GlucoWatch, the glucose values are not displayed on these systems. However, the Guardian CGMS features an audible alarm that sounds when glucose levels become too high or too low per parameters set by the patient and physician. The alarm is intended to prompt the patient to perform a finger stick blood glucose measurement, since a level is not provided with the sounding of the alarm.
• The FDA-approved labeling for the CGMS states, in part, that the CGMS is currently intended for occasional rather than everyday use, and is to be used only as a supplement to, and not a replacement for, standard invasive measurement. The CGMS is not intended to change patient management based on the numbers generated but to guide future management of the patient based on response to trends noticed. That is, these trends or patterns may be used to suggest when to take the finger stick glucose measurements to better manage patients.
• The GlucoWatch G2® Biographer marketed by Cygnus® is a noninvasive device worn like a wristwatch, which measures glucose in the interstitial fluid through the skin with a constant low level electric current by the process of reverse iontophoresis. Note: Neither the GlucoWatch nor the autosensors are available after July 31, 2008.
• The Guardian-RT (Real-Time) CGMS (Medtronic, MiniMed), is a provider prescribed device that is owned by the patient. It provides real-time information over extended periods of time, and has alarms twenty four hours a day. The approval statement indicates its use is for monitoring glucose levels in adults (ages 18 and older) with diabetes mellitus. It also states that values are not intended to be used directly for making therapy adjustments but to provide an indication of when a finger stick may be required, and that all therapy adjustment would be based on measurements obtained using a home glucose monitor and not on Guardian values.
• The Paradigm® Real-Time System, also marketed by Medtronic MiniMed, is a combination glucose monitor and insulin pump. The device allows the patient with diabetes to be alerted to fluctuating glucose levels and then the patient must confirm the reading with a finger stick glucose measurement before activating the insulin pump to administer additional insulin.
• The DexCom STS CGMS system (DexCom) is also for use by those with diabetes mellitus who are age 18 and older. Information from the premarket approval data submitted to the FDA indicates that the system is indicated for use as an adjunctive device to complement, not replace, information obtained from standard home glucose monitoring devices which use finger stick blood samples. Other real-time CGM systems are being studied, including systems for the pediatric age group.

Additional devices now have FDA approval:

• The FreeStyle Navigator CGM System (Abbott) - The sensor for this device can be worn on the back of the upper arm or on the abdomen. As with other CGM devices, information for this device also notes ”Before adjusting therapy for diabetes management based on the results and alarms from the FreeStyle Navigator system, traditional blood glucose tests must be performed.”
• The Paradigm REAL-Time System and Guardian REAL-Time System (Pediatric Versions) (Medtronic, MiniMed) are pediatric versions of previously approved devices. The approval of these devices includes the wording “All therapy adjustments should be based on measurements obtained using a home glucose monitor and not on the sensor glucose readings ….” This approval was based on the concordance of glucose results between those obtained with the sensor and with a glucose meter. The Paradigm system consists of an insulin infusion pump, the glucose sensor, and a transmitter.

In evaluating the continuous glucose monitoring systems, it is important to recognize that they may be used intermittently, e.g., time periods of 72 hours, or continuously.

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Prior Approval: 

Effective May 30, 2011 prior approval for continuous or intermittent monitoring is no longer recommended.  Documentation in the medical record should support that the clinical criteria outlined in the Policy section has been met.

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Policy: 

Intermittent monitoring of glucose levels in the interstitial fluid as a technique of monitoring insulin-requiring diabetes may be considered medically necessary for up to three days at a time for patients who:

• continue to perform four finger stick blood glucose monitoring levels each day AND

When one of the following criteria is met:

• unexplained frequent hypoglycemia episodes (less than 50 mg/dL), OR
• hypoglycemia unawareness as evidenced by seizures or loss of consciousness, OR
• discordant HbA1c and fingerstick blood glucose levels (such as the patient with consistent normal blood glucose levels at home but high HbA1c levels), OR
• frequent nocturnal hypoglycemia (less than 50 mg/dL), OR
• early morning fasting hyperglycemia (generally  known as the "dawn phenomenon" which is an abrupt increase in fasting levels of plasma glucose concentrations between 5 and 9 a.m., in the absence of antecedent hypoglycemia which is most pronounced in patients with type 1 diabetes because of their lack of ability to compensate by increasing endogenous insulin secretion.), OR
• prior to insulin pump therapy to determine basal insulin levels, and follow-up to verify adequate levels, OR
• pregnant, OR
• episodes of ketoacidosis, OR  
• hospitalizations for glucose out of control

Intermittent monitoring of glucose levels in the interstitial fluid as a technique of monitoring suspected non-diabetic hypoglycemia, such as may occur with Nesidioblastosis (islet cell dysmaturation syndrome) and insulinoma may be considered medically necessary for up to three days at a time.

Since time is needed to determine the efficacy of these treatment modifications, it is anticipated that when the above medical necessity criteria are met, the device could be used up to four times in 12 months.

Devices intended to monitor continuous interstitial glucose monitoring beyond three days (longer than 72 hrs) as an adjunct to standard care is considered medically necessary for patients with type 1 diabetes when the following criteria are met:

• use multiple daily doses of insulin or is on an insulin pump, AND
• continue to perform four finger stick blood glucose monitoring levels each day, AND
• Adequate metabolic control is not achieved despite frequent self-monitoring of blood glucose. This must be documented by at least one of the following:
  • hypoglycemic unawareness as evidenced by seizures or loss of consciousness, OR
  • frequent nocturnal hypoglycemia, less than 50 mg/dL, OR
  • unexplained wide fluctuations in blood sugar patterns over time (< 50 mg/dL, or > 150 mg/dL), OR
  • discordant HbA1c and fingerstick blood glucose levels (such as the patient with consistent normal blood glucose levels at home but high HbA1c levels), OR
  • pregnancy

Rationale:

Data presented to the U.S. Food and Drug Administration (FDA) advisory committee meeting consisted of studies validating the correlation between the measurements of glucose in interstitial fluid with the blood glucose measurements made with home monitoring devices. While the individual values between the two may vary, in general, the panel found that the overall trends in glucose levels detected by frequent measurements produced potentially clinically important information. However, there were no clinical data presented regarding improvements in HbA1c measurements or a decreasing incidence of hypoglycemic episodes in those whose antidiabetic medications were managed based on more frequent readings of interstitial fluid glucose. However, members of the advisory panel felt that more frequent measurements should extrapolate to improved diabetic management. For example, prior studies have shown that HbA1c levels are lowest among patients who have the highest frequency of daily blood glucose measurements.

The key clinical outcomes regarding the clinical utility of interstitial measurements of glucose, using either the Continuous Glucose Monitoring Systems or the GlucoWatch G2 Biographer, relates to their ability to provide either additional information on glucose levels leading to improved glucose control, or to improve the morbidity and mortality associated with clinically significant severe and acute hypoglycemic or hyperglycemic events. Because diabetes control encompasses numerous variables including the diabetes regimen and patient self-management, randomized controlled trials are important to isolate the contribution of interstitial glucose measurements to the overall diabetes management.

This policy is based on a 2003 TEC Assessment which reviewed the published controlled trials and offered the following discussion.

GlucoWatch Biographer

Chase and colleagues reported the results of a trial of 40 children with poorly controlled type 1 diabetes (HbA1c >8) who were randomized to diabetic management with or without glucose monitoring with a GlucoWatch device. Conventional glucose monitoring was performed 4 times daily in both groups. Those randomized to the treatment group were asked to wear the device 4 times per week for three months. After three months, all patients received Biographers and were followed up for six months. HbA1c values were determined at baseline and after one, three, six, and nine months. The median HbA1c level dropped from 8.9% to 8.4% in the treatment group, while in the control group the HbA1c increased from 8.6% to 9%. While this difference was statistically significant, it should be noted that the worsening of HbA1c in the control group was nearly as large in magnitude as the improvement in HbA1c seen in the Biographer group. There was no significant improvement in “fear of hypoglycemia” or quality of life between the two groups. In a second observational phase of the trial, all subjects were provided Biographer devices and observed over an additional six months. During this phase, the Biographer group maintained median HbA1c at 8.5%, and the control group improved median HbA1c to 8.6%, which was their original level. It was noted that the frequency of use of the Biographer declined over the course of the first phase of the study, and this may be why the Biographer group did not show further improvement in HbA1c over the subsequent 6 months of use.

Baseline characteristics of the two randomized study groups were reported to be without statistically significant differences. However, the baseline median HbA1c levels for these two groups were different by 0.3%, which is almost as large as the 0.4%–0.5% change observed within groups after provision of the Biographer, and this difference may have clinical significance. Also at baseline, slightly more patients in the control group used insulin pumps or received three or more insulin injections per day compared with the Biographer group, which had slightly more subjects receiving only two insulin injections per day. It is unknown whether these slight imbalances were a result of the small sample or whether there were any problems with randomization.

The authors do not discuss whether such differences might have influenced the observed results, but additional analyses adjusting for differences in potentially confounding baseline characteristics and exploring whether outliers could have influenced the results would be of interest. In addition, it is unclear whether subjects in the Biographer group received more frequent or more intense contact with physicians and the diabetes clinic. Biographer subjects were required to visit the clinic each week to download Biographer data; whereas the control group was able to fax back conventional fingerstick glucose meter data. This process may have provided more in-person opportunity for medical input in the Biographer group.

Interpretation of this study’s results should also take into consideration the observation that HbA1c levels may fluctuate over time, even without intervention, and variations of up to 1% may be observed clinically in the pediatric population. In this study, the control group’s HbA1c got worse during the intervention study, which partially contributed to the statistically significant difference between groups. Improvement in HbA1c has been observed in control groups in multiple other studies, most likely as a result of study effects (Hawthorne effect) in which participants in a trial achieve better compliance when results are being monitored. It is unclear why the control group got worse in this study, and this raises concerns over the reproducibility of the study.

Interpretation of the clinical significance of reducing HbA1c by 0.5% has been explored and both magnitude and durability of the improvement are important factors to consider. Eastman and colleagues presented an abstract of a decision analysis model based on the above study and reported that “the model predicts that treating 100 subjects under Biographer-guided standard care, if maintained for the life of the cohort, would prevent 20 cases of proliferative retinopathy, four cases of macular edema, six cases of blindness, 12 cases of clinical albuminuria, eight cases of end-stage renal disease, six cases of neuropathy and one amputation.” However, this model makes a variety of assumptions regarding the durability of the improvement.

In summary, Chase and colleagues conducted a small, randomized controlled trial and reported a small but statistically significant difference in the median HbA1c levels between groups after three months. However, the relatively small magnitude of incremental improvement in HbA1c levels needs to be interpreted in the context of potentially different baseline statistics between subjects in the two groups, potential study effects (Hawthorne effect) in the Biographer group in this unblinded trial, and potential influences of receiving more intense medical attention in the Biographer group. It would be very helpful to see the results of this trial confirmed by another larger, multicenter randomized controlled trial and to have further studies explore the durability of HbA1c improvements over time.

Continuous Glucose Monitoring Systems (CGMS)

Results of four randomized trials have been reported. The largest of them, which enrolled 128 adult patients with type 1 diabetes, is available in abstract only.  Among the 109 patients completing the three-month trial (the dropout rate was 15%), there was no statistically significant difference in HbA1c levels. Mean HbA1c levels in both the control and study groups declined from 9% at baseline to 8.3% at three months. Similarly, in another randomized study of 75 patients, there was no statistical difference in HbA1c levels after the three-month intervention. The other randomized studies  included only 11 and 27 patients, respectively. In 2004, Tanenberg and colleagues reported on a study of 128 patients randomized to insulin therapy adjustments using data from either the CGMS or self-monitoring of blood glucose (SMBG) using a home blood glucose monitor over a 12-week period. At 12 weeks, HbA1c levels and hyperglycemic event frequency and duration did not differ with any statistical significance in the treatment groups. However, at 12 weeks, events of hypoglycemia (glucose < or = 60 mg/dL) were found to be significantly shorter in the CGMS group than in the SMBG group (49.4 +/- 40.8 vs. 81.0 +/- 61.1 minutes per event, p = .009). The authors concluded that durations of hypoglycemia can be further reduced by adjusting insulin therapy with data from the CGMS rather than using SMBG data alone. Nevertheless, the biochemically defined measurements of hypoglycemia (without accompanying evidence of symptoms or a clinically significant hypoglycemic event) are not compelling outcomes. The clinical significance of these test results has not been established, i.e., there is insufficient evidence showing the link between increased duration of asymptomatic hypoglycemia and subsequent clinical outcomes.

2006 — 2007 Update

Additional studies continue to evaluate continuous glucose monitoring systems. Lagarde and colleagues found a slight improvement in HbA1c levels using CGMS compared to controls in children with type 1 diabetes. However, the difference did not reach statistical significance (p = 0.13). In a European study using a cross-over design, Deiss and colleagues reported that CGMS did not decisively influence glycemic control of the total study cohort of children and adolescents with type 1 diabetes.  They suggested that more frequent use of CGMS at shorter intervals may be of greater value. A recent review in The Medical Letter on Drugs and Therapeutics raised questions about the accuracy of these systems.

Garg, et al. reported in 2006 that in 91 patients with diabetes (75 were type 1) real-time continuous glucose monitoring was able to reduce glycemic excursions by reducing hyperglycemia without increasing the risk of hypoglycemia. They also indicated that this type of monitoring may reduce long-term complications of diabetes. Recently, Deiss, et al. reported on a three-month study of 81 children and 81 adults with stable type 1 diabetes who had HbA1c levels of 8.1% or greater. Patients were randomized to continuous real-time monitoring, continuous monitoring for three days every two weeks, or self-monitoring of blood glucose. At three months, 50% of patients with continuous real-time monitoring had a decrease in HbA1c of at least 1% compared to 37% of those with intermittent continuous monitoring, and 15 % of controls. These results suggest that continuous glucose monitoring may have potential for improving control in patients with diabetes; however, as the authors note, additional work is needed to determine long-term efficacy, clinical feasibility in patients with varying levels of glycemic control, and effect on rates of hypoglycemia.

April 2008 Update

The policy was updated with a literature review using MEDLINE from January 2007 through February 2008. No publications were identified that present results from randomized trials that show an impact of long-term continuous glucose monitoring on relevant patient outcomes. Recent publications continue to report results on case series and often do not clearly link to patient outcomes.

Guillod reported on a retrospective study that described findings from a group of 88 patients with type 1 diabetes who underwent a CGMS exam. The prevalence of nocturnal hypoglycemia (NH) was 67% (32% of them unsuspected). A measured hypoglycemia at bedtime (22–24 hr) had a sensitivity of 37% to detect NH, while a single measure 4 mmol/l or less at 03-hour had a sensitivity of 43%. In this study, NH measurements were not associated with morning hyperglycemias but with morning hypoglycemias. After 6–9 months, suspicions of NH decreased from 60% to 14% (p<0.001). The authors concluded that NH was highly prevalent and often undetected. Self-monitoring blood glucose at bedtime, which detected hypoglycemia, had sensitivity almost equal to that of 03-hour and should be preferred because it is easier to perform. Tubiana-Rufi reported on an uncontrolled study of 182 patients (children and adults) with poorly controlled type 1 diabetes. Using the Guardian RT system, which the authors indicated required 3 calibrations a day, resulted in improvement in HbA1c levels over 3 months. The DirecNet Study Group reported results of another non-comparative study of 30 patients with type 1 diabetes who used an insulin pump with the FreeStyle Navigator CGM system for 13 weeks. During this time, the mean HbA1c levels improved from 7.1% to 6.8% and the percentage of glucose values between 71 and 180 mg/dl increased from 52% to 60%. Two patients had severe skin reactions related to the sensor mount adhesive. Wilson and colleagues, as part of the Diabetes Research in Children Network (DirecNet), evaluated the accuracy and precision of the FreeStyle Navigator CGMS in 30 children with type 1 diabetes (mean age 11.2 years). The Navigator glucose values were compared with reference serum glucose values of blood samples obtained in an inpatient clinical research center and measured in a central laboratory and in an outpatient setting with a FreeStyle meter. Median absolute difference (AD) and median relative absolute difference (RAD) were computed for sensor-reference and sensor-sensor pairs. The median AD and RAD were 17 mg/dl and 12%, respectively, for 1,811 inpatient sensor-reference pairs, and 20 mg/dl and 14%, respectively, for 8,639 outpatient pairs. The median RAD between two simultaneous Navigator measurements (n = 1,971) was 13%. Ninety-one percent of sensors in the inpatient setting and 81% of sensors in the outpatient setting had a median RAD of 20% or less. The authors concluded that the Navigator's accuracy does not yet approach the accuracy of current-generation home glucose meters, but it is sufficient to believe that the device has the potential to be an important adjunct to treatment of youth with type 1 diabetes.

Several authors note that these results provide a compelling rationale for conducting a randomized controlled trial (RCT) of use of continuous glucose monitoring in type 1 diabetes. Recent advances in technology now allow linkage between the CGM device and an insulin pump. Halvorson reported on an uncontrolled pilot trail of 10 children with type 1 diabetes. The small size and lack of control group limit the ability to draw any conclusions from this study. Publications are also beginning to report on early trials of use of these devices in patients with type 2 diabetes. Wolpert discussed the skills needed for diabetes management using real-time monitoring and commented specifically on the role of calibration as well as understanding the lag between capillary and interstitial glucose levels. Given the lack of scientific data about the impact of CGM on clinical outcomes, this is considered investigational.

October 2008 Update

The policy was updated in October 2008 with a literature search using MEDLINE.

A recent systematic review of randomized studies identified 7 studies with 335 patients that fulfilled their inclusion criteria. Study duration varied from 12 to 24 weeks. This review concluded that compared with self-monitoring, CGMS was associated with a non-significant reduction in HbA1c levels and that evidence is insufficient to support the notion that CGMS provides a superior benefit over self-monitoring for HbA1c reduction. There was some indication from this review of improved detection of asymptomatic nocturnal hypoglycemia in the CGMS group.

The 2007 Standards of Medical Care by the American Diabetes Association (ADA) does not mention this technology in the section on assessment of glycemic control. Recommendations in this section are for self-monitoring of blood glucose 3 or more times daily for patient using multiple insulin injections. The 2008 Standards of Care from the ADA include a recommendation that “CGMS may be a supplemental tool to SMBG for selected patients with type 1 diabetes, especially those with hypoglycemia unawareness.” This recommendation is level E, based on expert consensus or clinical experience.

In December 2007 the Juvenile Diabetes Research Foundation (JDRF) completed recruitment for a 6-month trial at 10 centers of real-time CGMS in patients with type 1 diabetes. Results of this study, that randomly assigned 322 adults and children with type 1 diabetes to continuous glucose monitoring or self (home) monitoring, were released in 2008. 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 age 15 to 24 years or 8 to 14 years. Unlike many prior studies, this study was sufficiently large to detect a meaningful change in HbA1c levels between groups. The population in this study had relatively well controlled diabetes in that entry criterion was glycated Hb of 7 to 10% but about 70% had levels between 7 and 8%; in addition, over 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 age 25 or older where 83% of patients used the monitor 6 or more days per week.

2009–2010 Update

The MITRE trial 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. This was a 4-arm randomized, controlled trial conducted at secondary care diabetes clinics in 4 hospitals in England. In this study, 404 people aged over 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. Participants had 2 HbA1c values of at least 7.5% in the 15 months prior to entry and were randomized to one of four groups. Two groups received minimally invasive glucose monitoring devices (GlucoWatch Biographer or MiniMed Continuous Glucose Monitoring System [CGMS]); the CGMS 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 intent-to-treat 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 versus 57% still using the CGMS). In this study of unselected patients, use of continuous glucose monitors (CGMS on an intermittent basis) did not lead to improved clinical outcomes.

A study by the JDRF studied the potential benefits of continuous glucose monitoring (CGM) in the management of adults and children with well-controlled type 1 diabetes. In this study, 129 adults and children with intensively treated type 1 diabetes (age range 8-69 years) and HbA1c <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 (at or below 70 mg/dL) was less frequent in the CGM group than in the control group (median 54 vs. 91 min/day), but the difference was not statistically significant (P = 0.16). Time out of range (70 or less or greater than 180 mg/dL) was significantly lower in the CGM group than in the control group (377 vs. 491 min/day, 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 <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.

In a randomized study of 132 adults and children from France, Raccah and colleagues reported improved HbA1c levels (change in A1c of 0.96% vs. 0.55%) in patients who were fully protocol compliant for use of an insulin pump integrated with CGMS compared to those using a pump with standard glucose self monitoring.  This study is limited by its small sample size and also by lack of comparison to intermittent use of CGMS.

Summary

In summary, the available studies demonstrate that intermittent glucose monitoring provides a different type of data than results from finger stick glucose levels. In addition to providing more data points, it also provides information about trends (direction) in glucose levels. This additional information is most likely to benefit those patients with type 1 diabetes who do not have adequate control, including episodes of hypoglycemia, despite use of current best practices including multiple (4 or more) daily checks of blood glucose and multiple (3 or more) insulin injections or use of an insulin pump. Thus, based on the available data and supported by clinical input, the policy statement is changed to indicate that intermittent, i.e., 72-hour, glucose monitoring may be considered medically necessary in those whose diabetes is poorly controlled despite use of best practices.

The data supporting use of continuous (long-term) glucose monitoring are still limited. Using rationale similar to that noted above for intermittent monitoring, continuous monitoring can also be used, and can be considered medically necessary, to provide additional data for management of those who have recurrent, unexplained, severe symptomatic hypoglycemia, despite use of current best practices, that puts the patient or others at risk and for pregnant patients with type I diabetes.

Data to support use (that show improved outcomes) of devices that allow wireless connectivity between a continuous monitoring device and insulin pump are still lacking.

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Procedure Codes and Billing Guidelines: 

• To report provider services, use appropriate CPT* codes, Modifiers, Alpha Numeric (HCPCS level 2) codes, Revenue codes, and/or ICD-9 diagnostic codes. 
• HCPCS S1030 to report purchase of a continuous noninvasive glucose monitoring device, such as the GlucoWatch.
• HCPCS S1031 to report rental of continuous noninvasive glucose monitoring device, such as the GlucoWatch.
• HCPCS A9276 Sensor; invasive (e.g., subcutaneous), disposable, for use with interstitial continuous glucose monitoring system, 1 unit = 1 day supply
• HCPCS A9277 Transmitter; external, for use with interstitial continuous glucose monitoring system
• HCPCS A9278 Receiver (monitor); external, for use with interstitial continuous glucose monitoring system (does not require an insulin pump).    

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Selected References: 

• The Medical Policy Reference Manual developed by the Blue Cross Blue Shield Association Health Management Systems, based on Technology Evaluation Center (TEC) criteria.
• A review of the medical literature and recommendations from the Medical Policy Advisory Council (MPAC), which assists Wellmark’s medical directors in the development of medical policies. MPAC is comprised of practicing physicians from Iowa and South Dakota.
• Technology assessment brief. Continuous Glucose Monitoring System. Hays Alert 2000, June; vol. 3 (6): 5-6. 
• Tamada JA, Garg S, Jovanovic L, Pitzer KR, Fermi S, Potts RO, the Cygnus research teams. Noninvasive Glucose Monitoring, comprehensive clinical results. JAMA, 1999; 282:1839-1844. 
• Bode BW, Gross TM, Thornton KR, Mastrototaro JJ. Continuous glucose monitoring used to adjust diabetes therapy improves glycosylated hemoglobin: a pilot study. Diabetes Research and Clinical Practice 46 (1999) 183-190.
• 2003 TEC Assessment: Continuous or Intermittent Monitoring of Interstitial Glucose. Technology Evaluation Center; Available on line at http://www.bcbs.com/betterknowledge/tec/ 
• Chase H, Roberts P, Wightaman MD, et al. Use of the GlucoWatch biographer in children with type 1 diabetes. Pediatrics 2003;11(4): 1-10.
• Guerci B, Floriot M, Bohme P, et al. Clinical performance of CGMS in type 1 diabetic patients treated by continuous subcutaneous insulin infusion using insulin analogs. Diabetes Care2003;26:582-589.
• Tice JA. Continuous glucose monitoring devices in diabetes mellitus. California Technology Assessment Forum; 2003, October 8. 47 p.
• ECRI. Continuous subcutaneous glucose monitoring system for diabetes patients. Plymouth Meeting (PA): ECRI Health technology Information Service; 2002 August Target Report 519; 11 p. (ECRI Target Database). 
• ECRI. Continuous Subcutaneous Glucose Monitoring Systems for Diabetes. Plymouth Meeting (PA): ECRI Health technology Information Service; 2005 Jun 02. 10p. (ECRI Hotline Response).
• Chico A, Vidal-Rios P, Subira M et al. The continuous glucose monitoring system is useful for detecting unrecognized hypoglycemias in patients with type 1 and type 2 diabetes but is not better then frequent capillary glucose measurements for improving metabolic control. Diabetes Care 2003; 26(4):1153-7.
• Chase HP, Kim LM, Owen SL et al. Continuous subcutaneous glucose monitoring in children with type 1 diabetes. Pediatrics 2001; 107(2):222-6.
• Tanenberg R, Bode B, Lane W et al. Use of the Continuous Glucose Monitoring System to guide therapy in patients with insulin-treated diabetes: a randomized controlled trial. Mayo Clin Proc 2004; 79(12):1521-6.
• ECRI. Combined insulin pump and continuous glucose monitoring system for diabetes management. Plymouth Meeting (PA): ECRI Health technology Information Service; 2006 May 22. 9 p. (ECRI Hotline Response).
• ECRI. Guidelines for self-monitoring of glucose in patients with diabetes.  Plymouth Meeting (PA): ECRI Health technology Information Service; 2006 January 04. 9 p. (ECRI Hotline Response).
• Garg S, Zisser H, et al.  Improvement in glycemic excursions with a transcutaneous, real-time continuous glucose sensor: a randomized controlled trial.  Diabetes Care. 2006 Jan;29(1):44-50.
• Deiss D, Bolinder J, Riveline JP, et al. Improved glycemic control in poorly controlled patients with type-1 diabetes using real-time continuous glucose monitoring. Diabetes Care 2006: 29(12):2730-2.
• Continuous glucose monitoring. Med Lett Drugs Ther 2007; 49(1254):13-5.
• ECRI. Real-time continuous glucose monitoring (CGM). Plymouth Meeting (PA): ECRI Health technology Information Service; 2007 November Target Report 896; 16 p. (ECRI Target Database).
• American Diabetes Association. Standard of medical care in diabetes – 2008. Diabetes Care 2008;31(suppl 1):S12-54.
• The Juvenile Diabetes Research Foundation CGM Study Group. Continuous glucose monitoring and intensive treatment of type 1 diabetes. New England Journal of Medicine 2008 Sept 8; 359 [Epub ahead of print]
• ECRI. Real-time continuous glucose monitoring. Plymouth Meeting (PA): ECRI Health technology Information Service; 2008 August 29. 14 p. (ECRI Hotline Response).
• American Diabetes Association. Standards of medical care in diabetes--2010. Diabetes Care. 2010 Jan;33 (suppl)1:S11-61. No abstract available. Erratum in: Diabetes Care. 2010 Mar;33(3):692.  

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Policy History: 

Date                                       Reason                               Action

May 2011                              Annual review                    Policy renewed

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Wellmark medical policies address the complex issue of technology assessment of new and emerging treatments, devices, drugs, etc.   They are developed to assist in administering plan benefits and constitute neither offers of coverage nor medical advice. Wellmark medical policies contain only a partial, general description of plan or program benefits and do not constitute a contract. Wellmark does not provide health care services and, therefore, cannot guarantee any results or outcomes. Participating providers are independent contractors in private practice and are neither employees nor agents of Wellmark or its affiliates. Treating providers are solely responsible for medical advice and treatment of members. Our medical policies may be updated and therefore are subject to change without notice.

*Current Procedural Terminology © 2010 American Medical Association. All Rights Reserved.