Broadening Access to Continuous Glucose Monitoring for Patients With Type 2 Diabetes.

Persons from racial and ethnic minority populations, those in low-income groups, and other socially marginalized groups are disproportionately affected by type 2 diabetes and experience higher disease prevalence, poorer glycemic control, higher rates of diabetes complications, and higher prevalence of comorbid conditions.1,2 Achieving glucose targets that will reduce the risk of diabetes complications, particularly among highrisk groups, is critical to improve the health and well-being of those with diabetes and to reduce health care utilization and expenditures. Yet, diabetes control remains elusive. Selfmonitoring of blood glucose, while still a standard part of diabetes self-management, has not been shown to result in selfadjustments to insulin in primary care settings. This represents a significant opportunity gap because 30% of patients with type 2 diabetes are treated with some form of insulin.3 Real-time continuous glucose monitoring (CGM), which measures glucose levels in subcutaneous interstitial fluid as frequently as every 5 minutes, has been shown to improve diabetes control, reduce hypoglycemia, and be cost-effective for patients with type 1 diabetes.4,5 Less research has been conducted among patients with type 2 diabetes, but clinical trials involving patients using intensive insulin regimens (eg, basal/bolus insulin) have shown reductions in hemoglobin A1c (HbA1c) levels and shorter intervals of hypoglycemia.6,7 Several questions remain: Can the results of clinical trials of patients with type 2 diabetes be translated into usual care settings? Can patients with type 2 diabetes who use less intensive insulin regimens benefit from CGM? Can CGM be feasibly implemented in primary care settings, where most of type 2 diabetes management occurs? In this issue of JAMA, the randomized clinical trial (RCT) reported by Martens et al8 and the observational study reported by Karter et al9 provide new data that help provide answers to these questions. Martens et al8 conducted an RCT of CGM (n = 116) vs blood glucose meter (BGM) monitoring (n = 59) among adults with type 2 diabetes who were taking basal insulin without prandial insulin and were recruited from primary care practices. At 8 months, the mean HbA1c level improved from 9.1% to 8.0% in the CGM group and from 9.0% to 8.4% in the control group (adjusted difference, −0.4% [95% CI, −0.8% to −0.1%]). This effect size may have been greater if the control group had received usual care rather than instructions on how to self-titrate insulin based on BGM data. Compared with the BGM group, the time in range, or the amount of time spent in the target blood glucose range (70-180 mg/dL), was 3.6 hours per day higher, the mean glucose level was 26 mg/dL lower (95% CI, −41 to −12), and the time with glucose levels greater than 250 mg/dL was 3.8 hours per day less in the CGM group (all P < .001). There were also high rates of satisfaction among CGM users. Karter et al9 conducted a retrospective cohort study of 41 753 adult patients (36 080 with type 2 diabetes, 5673 with type 1 diabetes) who were treated with insulin and were receiving care at Kaiser Permanente.9 The authors followed the outcomes of those who initiated CGM (3806 patients) compared with those who did not; the CGM group primarily used basal/bolus insulin regimens, whereas the control group was treated with various types of insulin. Over the 4-year study period (which ended in December 2018), the authors reported a difference-in-difference reduction in HbA1c level of −0.40% (95% CI, −0.48% to −0.32%) and in rates of emergency department visits and hospitalization for hypoglycemia of 2.7% (95% CI, −4.4% to −1.1%). The net change in HbA1c level was greater among patients with type 2 diabetes (−0.56% [95% CI, −0.72% to −0.41%]) than among patients with type 1 diabetes (−0.34% [95% CI, −0.43% to −0.25%]) (P value for interaction = .003). In addition, a sensitivity analysis revealed a dose-response association between CGM adherence (0, 1, or ≥2 claims for CGM transmitters) and changes in HbA1c level and hypoglycemia health care utilization. These studies are important for several reasons. First, they confirm that CGM is a technology that can be effectively used by patients with type 2 diabetes to improve glycemic control. The trial by Martens et al8 recruited a diverse sample of patients who have disproportionately had barriers to fully accessing health care and health care–related technology and also have had disproportionately lower rates of adherence to diabetes treatment plans. Most patients in this RCT were non-White persons (53%), had less than a college degree education (55%), and did not have private insurance (58%). Exploratory analyses suggested that the reduction in HbA1c level did not differ across age groups, baseline diabetes control, education level, and diabetes numeracy, thus indicating a broad population benefit for CGM among patients with type 2 diabetes. The observational study from Karter et al9 demonstrated the benefits associated with CGM in usual care settings and found a greater improvement in diabetes control among patients with type 2 diabetes than those with type 1 diabetes. Second, the clinical trial by Martens et al8 demonstrated the promise of using CGM in primary care settings, where most patients with type 2 diabetes receive their care. This trial, in which study clinicians met with trial participants during Related articles pages 2273 and 2262 Opinion