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However, tight glucose control may require multiple measurements of blood glucose each day (i.e., 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 hypoglycemcia. 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's fasting blood glucose level might be within normal values, there might be undetected hyperglycemia postprandially, leading to elevated hemoglobin A1C values.

Recently, measurements of glucose in the 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. Two devices have received U.S. Food and Drug Administration (FDA) approval: 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). While the time intervals at which interstitial glucose is measured range from every 5 minutes (CGMS) to every  10 minutes (GlucoWatch), both types of monitoring have been referred to as continuous glucose monitoring. While both devices potentially eliminate or decrease the number of required daily fingersticks, it should be noted that, according to the FDA labeling, neither is intended to be an alternative to traditional self-monitoring of blood glucose levels, but rather serve as an adjunct, supplying additional information on glucose trends that are not available from self-monitoring. It is hoped that this information on glucose trends will lead to improved anti-diabetic regimens and ultimately normalization of hemoglobin A1C levels with a decreased risk of hypoglycemia.

Both devices rely on the same chemistry, i.e., the oxidation of glucose by glucose oxidase to produce hydrogen peroxide. Within the sensor, the hydrogen peroxide is further oxidized, ultimately producing electrons and generating a measurable electric current, which can be calibrated to the glucose concentration. The following discussion details other aspects of the two devices. Note: Neither the GlucoWatch nor the autosensors are available after July 31, 2008.

1. The GlucoWatch is similar in appearance to a wristwatch that is worn on the inner or outer surface of the forearm. A single use disposable component, called the AutoSensor, consists of gel collection disk and a series of electrodes. The device automatically measures glucose every 10 minutes for a 13-hour period, when it can be replaced by another AutoSensor. The device displays the most recent glucose level and can store the last 8,500 glucose readings along with their date and time. An audible alarm will sound if any reading is above a preset high, below a preset low, or if the reading is 35% or more below the previous reading. Each day, prior to use, the device must be calibrated with a fingerstick glucose test to allow for variability in skin permeability among individuals and at different skin sites.
   

   Although the noninvasiveness is an attractive quality of the device, it should be noted that the GlucoWatch is not intended to be used as an alternative to traditional fingerstick measures, but rather as an adjunct. Specifically, it is recommended that changes in medication should not be prompted solely by a GlucoWatch measurement, but confirmed by a fingerstick blood glucose measurement. In addition, as noted above, fingersticks are required to calibrate the device each day.

   The FDA approved labeling for the GlucoWatch states in part:

   • The GlucoWatch G2 Biographer is a glucose-monitoring device indicated for detecting trends and tracking patterns in glucose levels in adults (age 18 and older) and children/adolescents (age 7 to 17) with diabetes. This device is intended for use by patients at home and in healthcare facilities. The device is for prescription use only.
   • The GlucoWatch G2 Biographer is indicated for use as an adjunctive device to supplement, not replace, information obtained from standard home glucose-monitoring devices.
   • The Biographer is indicated for use in the detection and assessment of episodes of hyperglycemia and hypoglycemia, facilitating both acute and long-term therapy adjustments, which may minimize these excursions. Interpretation of Biographer results should be based on the trends and patterns seen with several sequential readings over time.
   
   
2. The Continuous Glucose Monitoring System (CGMS) (MiniMed) and the upgraded version, the Guardian CGMS, consist of a subcutaneously implanted 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 four fingerstick blood glucose measurements per day into the monitor. For the Guardian CGMS, it is recommended that the device be calibrated with fingerstick blood glucose levels every 12 hours at a minimum. The CGMS sensors are capable of transmitting values for up to three days, after which time it is removed and replaced with another by the patient, if additional monitoring is needed. The Guardian CGMS can store up to 21 days of data. Unlike the GlucoWatch, the glucose values are not displayed, and thus cannot be used by the patient for self-monitoring. The data captured in the monitor can be downloaded to a personal computer for review and use by a physician. The alarm is intended to prompt the patient to perform a fingerstick 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, 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 fingerstick glucose measurements to better manage the patients.

Recently, additional devices have been approved by the FDA that provide real-time continuous glucose monitoring. The Guardian-RT CGMS (Medtronic, MiniMed) which provides real-time information, received premarket approval in July 2005. The approval statement indicates its use for monitoring glucose levels in adults (ages 18 and older) with diabetes mellitus. It also indicates that values are not intended to be used directly for making therapy adjustments but to provide an indication of when a fingerstick 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 DexCom STS CGMS system (DexCom) was approved by the FDA in March 2006, and is also for use in those with diabetes mellitus who are aged 18 and older. Information from the premarket approval indicates that the system is indicated for use as an adjunctive device to complement, not replace, information obtained from standard home glucose monitoring devices. Other real-time CGMS systems are being studied, including systems for the pediatric age group.

During review for the policy update in 2008, additional devices were identified that now have FDA approval.  The FreeStyle Navigator CGM System (Abbott) was approved in March 2008.  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 (Peditric Versions) 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.

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, i.e., 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, symptomatic (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 keoacidosis.

Other uses of continuous monitoring of glucose levels in interstitial fluid as a technique of diabetic monitoring are considered investigational.

Best practices in diabetes control for patients with type I diabetes 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 I diabetes 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 diabetes control.

Investigative service is defined as the use of any treatment procedure, facility, equipment, drug, device, or supply not yet recognized by certifying boards and/or approving or licensing agencies or published peer review criteria as standard, effective medical practice for the treatment of the condition being treated and as such therefore is not considered medically necessary.

The coverage guidelines outlined in the Medical Policy Manual should not be used in lieu of the Member's specific benefit plan language.

4/2/2001: CPT code 84945 and ICD-9 procedure code 99.99 deleted. ICD-9 diagnosis code 250.23 and 250.33 added.

2/15/2002: Investigational definition added

2/25/2002: Code Reference, Sources and Place of Service sections updated

3/13/2002: E0609 deleted, 92950 (typo) should have been 95250, 99091 moved to non-covered

4/18/2002: Type of Service and Place of Service deleted

4/17/2003: FDA approved labeling for the GlucoWatch "first bullet" expanded to include children/adolescents (age 7 to 17)

6/12/2003: Clarification of changes 4/17/2003. GlucoWatch® G2™ Biographer (G2™ Biographer) information added to Description section.

9/5/2003: Policy reviewed, no changes

10/16/2003: GlucoWatch clarification statement added to "Policy" section

1/27/2004: Sources updated

2/10/2004: Sources updated

11/3/2004: Code Reference section reviewed, no changes

3/13/2006: Coding updated. CPT4 2006 revisons added to policy

3/20/2006: Policy reviewed, no changes

3/27/2007: Policy reviewed and updated. Covered codes table deleted. CPT codes 95250, 95251, and HCPCS S1031 moved to non-covered. Removed the following policy statement, "Continuous monitoring of glucose in the interstitial fluid is considered investigational except for patients with type 1 diabetes who have not achieved adequate glycemic control in spite of frequent self-monitoring of fingerstick blood glucose levels. BCBSMS will only approve the MiniMed monitoring system. Usage of which will be for a finite period of time (Rental)."

7/19/2007: Reviewed and approved by MPAC

12/17/2007: Coding updated. CPT/HCPCS 2008 revisions added to policy.

4/25/2008: Policy reviewed, description section updated

12/31/2008: Code reference section updated per the 2009 CPT/HCPCS revisions

1/8/2009: Policy reviewed and updated. Policy statement updated to allow intermittent monitoring in patients with type I diabetes whose diabetes is poorly controlled, prior to insulin pump initiation to determine basal insulin levels and according to best practice guidelines. Policy guidelines updated to include Best Practice guidelines.Codes updated to reflect covered codes.

04/26/2010: Added “or Intermittent” to the policy title. Policy description and statement unchanged.  FEP verbiage added to the Policy Exceptions section. Deleted outdated references from the Sources section.

04/20/2011: Policy reviewed; no changes.

04/26/2012: Policy reviewed; policy statement unchanged. Policy guidelines updated to state the following:  Several insulin pump systems (e.g., 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. Insuline pumps are addressed in the External Infusion Pumps policy.

Blue Cross Blue Shield Association Policy # 1.01.20

The code(s) listed below are ONLY covered if the procedure is performed according to the "Policy" section of this document.

Covered Codes