Abstract
IMPORTANCE: Cognitive impairment and glycemic control have a bidirectional association. Understanding the impact of continuous glucose monitoring (CGM) vs self-monitoring of blood glucose (SMBG) is important for treating older adults with Alzheimer disease and related dementias (ADRD) and diabetes that is treated with insulin. OBJECTIVE: To compare the risks of glycemic outcomes and related adverse events between CGM users and prevalent SMBG users in insulin-treated older adults with ADRD and diabetes. DESIGN, SETTING, AND PARTICIPANTS: This retrospective, prevalent-new user cohort study utilized a nationwide, 15% random sample of Medicare claims data (Parts A, B, and D) from January 2016 to December 2020 to ensure balanced cohorts. Insulin-treated older adults (≥66 years) with ADRD and diabetes were included. Individuals in hospice care or with a professional CGM use were excluded. Analysis was carried out from August 2023 to December 2024. EXPOSURE: Therapeutic CGM use vs prevalent SMBG use. MAIN OUTCOMES AND MEASURES: Primary outcomes included hypoglycemia hospitalizations, hyperglycemia crisis, and all-cause mortality; falls and all-cause hospitalizations were secondary outcomes. Upper respiratory tract infections served as a negative control outcome. A 1:1 propensity score matching with a 0.25 caliper was carried out for confounding control. Cox proportional hazards models were used for outcome analysis. RESULTS: In this cohort of 2022 insulin-treated older adults with diabetes and ADRD (1011 CGM users and 1011 SMBG users; mean [SD] age, 76.4 [6.7] years; 1133 female [56.0%]), CGM use was significantly associated with lower risk of all-cause hospitalization (hazard ratio [HR], 0.86; 95% CI, 0.76-0.96) and mortality (HR, 0.57; 95% CI, 0.48-0.67) compared with SMBG use. CGM use had lower point estimates for hypoglycemia hospitalization (HR, 0.66; 95% CI, 0.40-1.08) and falls (HR, 0.86; 95% CI, 0.68-1.08) and higher point estimates for hyperglycemia crisis (HR, 1.38; 95% CI, 0.99-1.94) vs SMBG use, but these findings were not significant. Exploratory subgroup analyses showed varied benefits. The negative control outcome showed no significant differences across analyses. CONCLUSIONS AND RELEVANCE: In this cohort study of insulin-treated older adults with ADRD and diabetes, CGM use was associated with improved long-term clinical outcomes. Pragmatic (ie, evaluating the effectiveness of healthcare interventions in everyday settings) trials are needed to validate these findings and to assess the feasibility of CGM use in this population.