Continuous Glucose Monitoring (CGM) Is a Tool,Not a Reward: Unjustified Insurance Coverage Criteria Limit Access to CGM

Current criteria

The current eligibility requirements for CGM coverage are prime examples of how scientific evidence is being ignored or dismissed by the Centers for Medicare and Medicaid Services (CMS) and many private insurers. Although both government and most private insurers cover the newest classes of diabetes medications, including glucagon-like peptide-1 receptor agonists (GLP-1 RA) and sodium-glucose transport protein 2 inhibitors (SGLT2-I), coverage for CGM remains unattainable for the majority of individuals with T2D due to restrictive coverage policies that are both onerous and scientifically unfounded.

We conducted an extensive internet search to ascertain the eligibility criteria used by CMS and the top five private insurers to determine the medical necessity for CGM use by beneficiaries and health plan members (Table 1). Among the CMS health plans, we found that CGM coverage, in general, was inconsistent. Whereas the Medicare clearly defines its eligibility criteria, Medicaid coverage criteria for CGM is inconsistent among states, constantly changing and, in many states, not available. The most recent data show that 17 states cover T1D only, 14 cover both T1D and T2D, 4 cover pediatric patients only, and 16 (including Washington DC) provide no CGM coverage. ²⁹ However, eligibility criteria in the states that do offer coverage often mirror the current Medicare requirements. Only three of the top five private insurers (Aetna, ³⁰ Humana, ³¹ United Healthcare Medicare Advantage ³² ) provided eligibility guidance to its members or potential members. Information about CGM eligibility was not readily available on the Anthem or Cigna websites.

As given in Table 1, two of the three private plans include criteria that are similar to Medicare requirements ³³ regarding blood glucose monitoring (BGM) frequency (≥4 times daily) treatment with intensive insulin regimens (≥3 times daily injections or insulin pump). Although all the plans require insulin therapy, Medicare and United Healthcare impose the added requirement of frequent insulin dosage adjustments but do not consider having a history of hypoglycemia as an indication for CGM eligibility. They also ignore the demonstrated advantages of telemedicine visits by requiring in-person consultations at CGM initiation and 6-month follow-up visits.

Is a history of diabetes self-management behaviors relevant to optimal CGM use and outcomes?

The answer is no. Large clinical trials have shown that successful use of CGM is not associated with history of BGM daily frequency, use glucose data for insulin adjustments or specific insulin regimens Table 2.

BGM frequency

Review of the reported baseline characteristics of participants in large randomized controlled trials (RCTs) clearly demonstrates that individuals who performed BGM <4 times /day achieved similar glycemic improvements compared, when switched to CGM, with those testing at a higher frequency. For example, in the recent IMPACT ³⁴ and REPLACE ⁴ studies, there were no significant differences in glycemic outcomes between participants who were testing <4 times daily and those testing ≥4 times daily before using CGM. Findings of “nonassociation” between baseline BGM frequency and glycemic outcomes were also observed in the DIAMOND T1D ⁴³ and DIAMOND T2D ¹ trials. In a subsequent analysis of the older T1D and T2D individuals (age 67 ± 5 years) included in the DIAMOND trials, significant hemoglobin A1c (HbA1c) reductions were achieved with CGM versus BGM use regardless of baseline BGM frequency; 52% of CGM users reported performing BGM <4 times/day before initiating CGM. ² Moreover, a recent retrospective claims database analysis of 12,521 T1D and T2D patients found that CGM use was significantly associated with reductions in acute diabetes-related events (from 0.245 to 0.132 events/patient-year (P < 0.001), and that these reductions were not associated with prior BGM frequency, <4 versus ≥4 times daily. ⁴⁴ In a recent claims database study that assessed the impact of flash CGM compared with traditional BGM, investigators found no relationship between prior BGM monitoring frequency and significant reductions in hospitalizations for hypoglycemia and hyperglycemia. ⁴⁵

Use of BGM data to make frequent insulin adjustments

In addition, none of the protocols for the RCTs listed in Table 2 required participants to use glucose data for frequent insulin adjustments. Requiring patients to provide documentation of frequent dosage adjustments based on BGM readings is unfounded; we know of no studies that have shown a relationship between this requirement and clinical outcomes. Moreover, it ignores the other benefits of CGM regarding reductions in hypoglycemia as demonstrated by Pratley et al. ³⁶

Three or more daily insulin injections

Similarly, the large RCTs provide no indication that prior use of intensive insulin regimens, multiple daily insulin injection (MDI) or insulin pump, is a prerequisite for CGM. In fact, large retrospective database analyses of T2D patients treated with less-intensive insulin regimens or oral antidiabetic medications have shown that CGM use was associated with significant reductions in HbA1c levels ^46,47 and health resource utilization, including diabetes-related hospitalizations and emergency room care. ⁴⁸

Even intermittent use of CGM has been shown to improve glycemic outcomes and psychological measures. In an earlier RCT involving individuals with T2D treated with basal insulin only, noninsulin medications, and diet/physical activity, Vigersky et al. demonstrated that intermittent use of CGM (2 weeks on/1 week off) versus BGM over 3 months resulted in significant HbA1c reductions. ¹³ Ehrhardt et al. showed that these improvements persisted throughout a 52-week follow-up period. ⁴⁹ In an economic analysis of this cohort, CGM was found to be cost-effective, and that repeated CGM use would likely result in additional cost savings. ⁷ In two more recent studies of individuals with noninsulin-treated T2D who were enrolled in a comprehensive telemedicine program, intermittent CGM use resulted in significant HbA1c reductions. ^21,50

Are frequent therapy adjustments required to optimize CGM use?

The answer is no. It is well recognized that CGM offers a clear advantage over BGM in assisting users when calculating their insulin dosages. However, a more significant benefit is its ability to detect and alert users to immediate and impending hypoglycemia. Problematic hypoglycemia remains a major barrier to effective diabetes self-management ⁵¹ and is particularly concerning in older diabetes patients and those with long duration of diabetes who are higher risk for severe hypoglycemia (<54 mg/dL) and impaired hypoglycemia awareness. ^{52 –58}

In older Medicare beneficiaries, severe hypoglycemia is the most common acute glycemic event in those treated with insulin or sulfonylurea therapy ⁵⁸ and is associated with significant adverse outcomes, including acute cardiovascular events, ⁵⁹ fall-related fractures, ⁶⁰ dementia, ^61,62 and mortality. ^63,64 The increased risk and clinical consequences of hypoglycemia are evidenced in a retrospective study of Medicare beneficiaries of age ≥65 years from 1999 to 2011 that showed an 11.7% increase in inpatient admission rates for severe hypoglycemia (from 94 to 105 admissions per 100,000 person-years). ⁵⁸

Although Aetna and Humana eligibility criteria recognize the utility of CGM in preventing hypoglycemia, The Medicare and United Healthcare Medicare Advantage plans seem to dismiss the importance of this capability (Table 1). This omission is particularly troubling given that these plans cover individuals of age ≥65 years, a growing population that comprises ∼26.8% of all diabetes in the United States. ⁶⁵

Moreover, none of the plans recognize that all individuals treated with any insulin regimen or sulfonylurea therapy are at risk for severe hypoglycemia. ^{37,51 –57,66 –74} In one study that included ∼32,000 U.S. T2D adults treated with noninsulin therapy, investigators reported that the probability of severe hypoglycemia was almost doubled in >45% patients who received intensive treatment with noninsulin medications. ⁶⁷

Similar risks for hypoglycemia were seen in a retrospective analysis of a large German/Austria database. ⁶⁸ Within a cohort of 29,485 T2D adults treated with sulfonylureas, 826 (2.8%) experienced at least one severe hypoglycemic event during their most recent year of sulfonylurea treatment. Among these, 531 (1.8%) experienced coma and 501 (1.7%) were hospitalized at least once. ⁶⁸

Conversely, use of CGM has been shown to reduce the risk of severe hypoglycemia in both insulin-treated and noninsulin-treated diabetes. ^36,39,40,66 In a cohort of 203 older T1D adults (≥60 years) randomized to CGM or BGM over a 6-month period, CGM use was associated with significant reductions in severe hypoglycemia incidence rates (per 100 person-years) compared with BGM (1.9 vs. 22.4, respectively, P = 0.02). ³⁶ It was also associated with reductions in the percentage of time spent <70 mg/dL (from 5.1% to 2.7%) versus increases with BGM use (from 4.7% to 4.9%), P < 0.001.

Among T2D patients treated with less-intensive insulin regimens or oral antidiabetic medications, large retrospective database analyses of CGM use were associated with significant reductions in HbA1c levels ^46,47 and diabetes-related hospitalizations/emergency room utilization. ⁴⁸ Importantly, CGM use reduces hypoglycemia fear and increases patient and family members' confidence in their ability to manage their diabetes, ^37,66,75,76 This is particularly important in individuals with problematic hypoglycemia who often decrease or omit their insulin and maintain their glucose levels in the hyperglycemia range due to fear of hypoglycemia. ^77,78

Are in-person clinician visits essential to assess and monitor CGM users?

The answer is no. Evidence from meta-analyses and systematic reviews clearly demonstrates that the use of telemedicine interventions to monitor glycemic status in individuals with T1D and T2D is associated with significant HbA1c reductions, ^{79 –84} lower incidence of severe hypoglycemia, ⁸³ reduced diabetes-related distress, ²² and greater adherence to prescribed therapy. ⁸⁵ In a recent RCT that followed 74 adults with T1D for 1 year, investigators reported similar HbA1c improvements between those supported by telemedicine consults and those receiving usual care through in-person clinic visits. ⁸³

The value and utility of telemedicine technologies are most apparent when CGM users opt to transmit their data to their clinician for analysis. All current CGM manufacturers provide download software that utilizes variations of the ambulatory glucose profile (AGP). The AGP software program instantly analyzes the data and provides a standardized report that informs the clinician about the individual's current glycemic status relative to achieving established targets for glucose control. ⁸⁶ Clinicians can then initiate a telemedicine consult to review the AGP report with the patient. These interactions help patients better understand their disease and treatment regimen, which facilitates greater engagement and treatment adherence. ⁸⁷ The importance and utility of telemedicine consults have been clearly demonstrated throughout the COVID-19 pandemic, which has prompted a dramatic restructuring of health care delivery. ^{88 –92} Telemedicine visits can also eliminate the need for in-person training for those with internet access.

In a recent study, Gal et al. assessed the feasibility of initiating CGM training in a cohort of 34 T1D adults. ⁹³ During the study, participants completed three virtual clinic visits conducted by certified diabetes care and education specialist (CDCES) outside the clinical care setting. The CDCES served as the participants' primary contact during the study. The virtual sessions included training in sensor insertion, use of alarms/alerts, downloading CGM data, data interpretation, modifying health behaviors, and other aspects of diabetes self-management. At 12 weeks, mean HbA1c decreased from 8.3 at baseline to 7.2 (P < 0.001) with a significant increase in percentage of time spent in target glucose range per day, from 48% to 59% (P < 0.001). Substantial improvements in quality-of-life measures, including reductions in diabetes distress, increased satisfaction with glucose monitoring, and fewer perceived technology barriers to management, were also reported.

Are documentation requirements impeding prescription of CGM in eligible individuals?

The answer is we do not know, but it is entirely likely. A burdensome by-product of the current CGM eligibility criteria is the extensive documentation required to obtain coverage. ⁹⁴ Adhering to the requirements requires clinicians and office staff to gather and submit extensive documentation that includes patient records that provide detailed information about each patient's glucose testing, insulin adjustments, and other self-management data and activities. In addition, they must include their own notes that justify the CGM prescription. Faced with these obstacles, many busy clinics are unable or unwilling to comply with the requirements and simply refuse to prescribe CGM to their patients.

To our knowledge, no definitive studies have been conducted regarding the extent of these refusals. However, we do know that onerous documentation requirements are negatively impacting patient care. On a 2017 survey of 1000 clinicians, 92% of respondents said that documentation requirements for obtaining authorization for various medications and medical devices delay patient treatment and negatively affect clinical outcomes. ⁹⁵

What is particularly puzzling is that CMS only provides coverage for three glucose test strips per day yet requires ≥4 times daily testing with supporting documentation. So, to qualify for CGM coverage, beneficiaries must pay out-of-pocket or their physician must be willing and able to collect and organize patient data at each visit, construct and document a compelling argument supporting the patient's need for extra test strips, complete the necessary paperwork, and then submit the claim to an approved supplier to obtain coverage. Again, many clinicians may not have the time to perform these additional tasks.

Compounding the problem is the lack of clarity the CMS provides to the durable medical equipment suppliers who make the final decision when submitting claims. In essence, these suppliers must determine whether the clinician's documentation supports the claim for “medical necessity,” which is not clearly defined by CMS. As a result, claims are often rejected by suppliers to avoid potential financial penalties that could be imposed by CMS audits if they guess wrong.

Traditional approaches to diabetes management are ineffective and unsustainable

Persistent hyperglycemia significantly increases the risks for both acute ^52,96,97 and long-term complications ^{98 –103} with associated increased costs. ¹⁰⁴ Thus, preventing or reducing the severity of acute and long-term diabetes complications remains a primary goal of diabetes management, and maintaining optimal glycemic control is central to achieving this goal. ^105,106

However, despite advances in diabetes medications, glucose monitoring technologies, and insulin-delivery systems, a significant proportion of individuals with diabetes are not achieving their individual glycemic targets. ^{107 –111} A major driver of suboptimal glycemic control is therapeutic inertia. Although national and international clinical guidelines recommend that treatment should be escalated if individualized glycemic targets are not met within 3–6 months of initiation of treatment, ¹⁰⁵ intensification of treatment when clinically indicated often does not occur. ¹¹²

Several barriers to therapy intensification have been cited. ^{113 –116} Patients are often reluctant to adhere to their prescribed therapy due to negative perceptions about the efficacy of their treatment, lack of appropriate knowledge about managing their diabetes, and concerns about hypoglycemia. ¹¹⁷ Clinicians are challenged to intensify therapy by different barriers, including restrictions on time and resources, ^118,119 inaccurate or incomplete glucose data, ^{120 –122} lack of decision support tools, ¹²³ and concerns about hypoglycemia. ¹²⁴

Utility of CGM Versus BGM

It is widely recognized that frequent glucose monitoring is critical for achieving glycemic targets and reducing hypoglycemia in individuals treated with antihyperglycemic medications such as insulin and sulfonylureas. It is particularly important for elderly patients to systematically monitor their glucose due to their increased risk for severe hypoglycemia. ^{125 –127} Although BGM through fingerstick capillary blood sampling is the most common method for glucose testing, it cannot detect the velocity or direction of rapidly changing glucose levels without frequent testing. Because many individuals find BGM painful and burdensome, they often do not test as frequently as needed to detect immediate or impending hypoglycemia. In a recent study of 33 T2D adults treated with antihyperglycemic oral medications, Siddiqui reported that 61.9% did not use BGM in their daily regimen. ¹²⁸

Unlike BGM, which provides only a single glucose value, CGM continuously samples interstitial glucose and transmits the data to the user's handheld reader or smartphone app, automatically or when the user scans the sensor. The data are displayed in both numerical and graphical presentations that provide information about the user's current glucose level, recent glucose trend, and direction/velocity of changing glucose. This information facilitates more informed decision making regarding medication adjustments and lifestyle behaviors (e.g., meal size, timing of physical activity). Importantly, it enables them to take immediate action to mitigate current or impending acute glycemic events.

Today's CGM systems also feature active alarms and alerts that warn users of high or low glucose, offering additional safety advantages. ^{129 –131} These features can be critical for some individuals such as those who experience frequent hypoglycemia, severe hypoglycemia, and/or impaired hypoglycemia awareness. ^40,132 BGM cannot provide information on glucose levels and cannot provide alerts about urgent glucose levels between tests.

Because CGM presents the glucose trend and direction/rate of changing glucose in graphical formats, users are able to visualize their current glucose status, which both demonstrate the impact (and efficacy) of their medications and facilitate a greater understanding of the “cause and effect” of their health behaviors. Moreover, the use of graphical data formats is essential for the many individuals with diabetes who are challenged with poor numeracy skills. As reported in several studies, poor numeracy is common among and associated with poor glycemic control with diabetes. ^{133 –136}

An additional feature of current CGM devices is the ability to share data with others. A recent study of device usage in 15,000 CGM users found that 94.8% of respondents utilized the sharing feature and had at least one follower. ¹³⁷ Investigators reported that the presence of at least one follower was associated with lower mean glucose values, greater time spend in target range (70–180 mg/dL), less time spent in hypoglycemia and hyperglycemia, and significantly more frequent CGM utilization. This suggests that use of the sharing feature contributed to more timely interventions and/or increased engagement among the caregivers or other followers.

Importantly, glucose data can be downloaded for retrospective analysis using efficacy metrics that are unique to CGM technology. These include time and percentage of time spent in various glucose ranges (time in range, time below range, and time above range). ^86,138 These metrics have been adopted by several national and international medical organizations. ⁸⁶