INTRODUCTION

Continuous glucose monitors (CGMs) improve diabetes control and reduce harms from hypoglycemia among adults with diabetes who use insulin.1 As evidence for CGM benefits expanded beyond Type 1 diabetes, in 2022, the American Diabetes Association began recommending CGMs for all adults using insulin, regardless of diabetes type or insulin regimen.2 However, uptake of new medical technology often lags behind the evidence and is prone to socioeconomic disparities.3 Therefore, we sought to describe recent trends in CGM use among adults with diabetes using insulin in the United States.

METHODS

This study used data from the Behavioral Risk Factor Surveillance System (BRFSS), an annual telephone survey supported by the Centers for Disease Control and Prevention and conducted by all 50 states and DC.4 Adults (aged ≥ 18 years) who self-reported having diabetes (any type) and using insulin were included in the study. Between 2014 and 2021, these individuals were asked how often they check their blood sugar, and respondents with CGMs were coded as checking 99 times per day. Questions about diabetes are part of an optional BRFSS module, and a subset of states asked these questions each year, often alternating years. To optimize sample size, data from odd years between 2015 and 2021 were included in the analysis, representing 28 to 38 states each year, and a total of 43 states and DC. Rates of CGM use (per 1,000), accounting for the complex sampling design of BRFSS, were estimated for each study year using Stata 18.0, overall and in subgroups of race/ethnicity, education, income, and insurance status. Average annual percent changes (AAPCs) were estimated using Joinpoint 5.1. In a sensitivity analysis, only data from 17 states and DC, which reported every year of the study, were included.

RESULTS

Across all study years, 49,423 participants representing 28,492,440 adults with diabetes using insulin were included. Characteristics were mostly similar in 2015 and 2021, although there was a higher percentage of non-Hispanic White race/ethnicity and college education among participants in 2021 (Table 1).

Table 1 Baseline Weighted Participant Characteristics, 2015 and 2021
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Overall, the rate of CGM use increased from 1.4 to 21.1 per 1,000 between 2015 and 2021, with an AAPC (95% CI) of 56.1% (49.7, 65.2) (Table 2). There were large socioeconomic disparities in CGM use: in 2021, the rate per 1,000 (95% CI) was 29.9 (23.2, 38.5) among non-Hispanic White adults compared with 4.4 (1.6, 11.7) among non-Hispanic Black adults. However, increasing trends were also observed among subgroups with disadvantage: among adults with annual household incomes < $35,000, CGM use increased from 0.4 to 15.9 per 1,000 between 2015 and 2021, with an AAPC of 85.4% (60.8, 137.9). Patterns were similar for the sensitivity analysis only including states that reported every year of the study, though comparisons were limited by small cell sizes (data not shown).

Table 2 Trends in Continuous Glucose Monitor Use, 2015–2021
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DISCUSSION

Between 2015 and 2021, self-reported CGM use among adults using insulin increased severalfold, although overall uptake remained low and there were persistent socioeconomic disparities. Nevertheless, increasing trends were observed among respondents with low income and public insurance, which may reflect, in part, expanding Medicare and Medicaid coverage of CGMs during the study period.3

Limitations include the potential for miscoding, lack of representation of all states during the study period which limits generalizability, and limited statistical precision in some subgroups due to insufficient sample size.

These results highlight the need to close large gaps in CGM uptake in order to provide guideline-based care for all adults using insulin. As CGMs are prescribable devices, measures to improve pharmacoequity5 may help address specific barriers faced by groups with adverse social and structural determinants of health.