Background: Despite increased use of continuous glucose monitoring (CGM) systems, studies to quantify patterns of CGM use are limited. In December 2018, a policy change by a commercial insurer expanded coverage of CGM through the pharmacy benefit, creating an opportunity to evaluate the impact of this change on CGM utilization. Research Design and Methods: Pharmacy and medical claims from 2016 to 2020 were used to estimate the prevalence of CGM use among insulin users with type 1 diabetes mellitus (T1DM) or type 2 diabetes mellitus (T2DM) before and after the policy change. Change in CGM use was assessed using an interrupted time series design. Results: At the beginning of the study period, 18.8% of T1DM patients and 1.2% of T2DM patients used CGM. Use rose to 30.5% and 6.6% in the quarter before the policy change. The policy resulted in an immediate 9.5% (P < 0.0001) and 2.8% (P < 0.0001) change in use and increased the rate of quarterly change by 0.5% (P = 0.002) and 0.8% (P < 0.0001). At the end of the study period, 58.2% and 14.9% of T1DM and T2DM patients used CGM. Conclusion: CGM use significantly increased after addition to the pharmacy benefit. Rate of change in CGM use was lower in T1DM compared to the T2DM population, but overall use remained higher among patients with T1DM. Increased CGM use in the population studied aligns with those whose clinical guidelines suggest would most likely benefit. Additional work is needed to evaluate the impact of this benefit change on health care spending and outcomes.
Keywords: Continuous glucose monitor use; Type 1 diabetes; Type 2 diabetes.