Use of Continuous Glucose Monitoring Devices Varies by Age for Patients With T1D

Use of continuous glucose monitoring (CGM) devices varies with age for patients with type 1 diabetes (T1D), with patients in middle adulthood being the most common users, according to a study published in JAMA Network Open.

While small, remote CGM devices are recommended as the standard for glucose monitoring for T1D, trends in CGM use suggest age-related barriers to CGM use and barriers to CGM coverage for Medicare patients, which may reflect CMS policies that were undergoing change at the time the data were collected.

For years, Medicare did not cover CGM, requiring users to pay out of pocket for a management tool that had become standard of care. Although Medicare changed its policy to allow CGM coverage in January 2017, implementation was not uniform among Medicare’s administrative contractors.

Additional changes in 2021 opened Medicare CGM coverage to more types of devices and no longer require users to perform finger stick tests of their blood glucose 4 times a day.

Researchers conducted a cross-sectional study to examine age, the probability of CGM use, and the association of CGM use with glycemic control across the lifespan for patients with T1D. They used data from the national T1D Exchange Registry (2017-2018) for individuals 10 to 85 years old. The registry included data from patients with T1D collected through medical record extraction and patient questionnaires at 80 US clinics nationwide.

Researchers controlled for health insurance, sex, annual household income, race and ethnicity, education level, and insulin delivery method in their analyses.

The sample included 19261 patients aged 10 to 85 years with T1D. The mean (SD) age of the sample was 27.58 (17.65) years. While sex was unknown for 0.2% of the sample, the rest of the sample was 50.59% female and 49.21% male.

Mean (SD) glycated hemoglobin (A1C) among participants was 8.57% (1.81%). A total of 5779 (30%) of patients reported CGM use.

Researchers found that the adjusted probability of CGM use decreased in adolescence and then increased afterward until approximately age 40. CGM use remained relatively constant from age 40 to age 60, before decreasing until age 75.

CGM use was found to be associated with lower A1C levels across age compared with nonuse. However, this association waned as age increased.

The adjusted mean difference in A1C levels among patients using CGM relative to nonusers was −0.70% at age 10 years (ie, 0.70% lower among users). The adjusted mean difference decreased to −0.62% at 20, −0.55% at 30, −0.48% at 40, −0.41% at 50, −0.34% at 60, −0.27% at70, −0.20% at 80, and −0.16 at 85 years.

These results indicate that CGM use varies across age, with the highest adjusted probability occurring in middle adulthood. The probability of CGM utilization decreased with increasing age in older adulthood. The authors suggest that this trend reflects the barriers that Medicare patients face regarding CGM coverage.

The authors also suggest that the clinically significant differences in A1C levels (> 0.50%) among CGM users and nonusers amount youth and adult populations underscore the need to identify age-related barriers to CGM use.

Decreases in A1C differences over the lifespan suggest that adolescence is partly associated with higher A1C levels. However, the authors note that this could also suggest possible survivorship bias, as older individuals with T1D may have better glycemic control regardless of CGM use.

They also propose that there are likely benefits to CGM use among older adults not reflected in the A1C outcome, such as reduced hypoglycemia, which should be explored.

The study has some limitations. The cross-sectional design precludes causal inference. Additionally, the predominance of non-Hispanic White individuals in the sample limits the generalizability of the findings to other racial and ethnic groups.

The authors encourage further work to explore patterns in CGM use and severe hypoglycemia, diabetic ketoacidosis, and health care utilization over the lifespan.

Reference

Weinstein J M, Kahkoska A R. Association of continuous glucose monitoring use and hemoglobin A1C levels across the lifespan among individuals with type 1 diabetes in the US. JAMA Netw Open. 2022;5(7):e22223942. doi:10.1001/jamanetworkopen.2022.23942. Published July 27, 2022.