Diabetes Treatment Intensity and Accelerated Functional Decline in Older Adults: Evidence From the Health and Retirement Study

Background: Functional limitation and disability are major consequences of diabetes in older adults. However, whether diabetes treatment intensity predicts accelerated functional decline beyond diabetes status alone remains unclear. Methods: This longitudinal cohort study used the RAND HRS Longitudinal File 2022 (V1), including 42,141 respondents and 253,244 person-wave observations across up to 15 biennial waves (1994–2022). Participants were categorized by highest reported diabetes treatment intensity: no diabetes, non-insulin treatment, or insulin. Primary and secondary outcomes were counts of activities of daily living (ADL) and instrumental activities of daily living (IADL) limitations, respectively, each ranging from 0 to 5. The primary outcome was the treatment group–by–time interaction, representing excess limitation accumulation per decade relative to participants without diabetes. Results: Insulin treatment was associated with a steeper rate of ADL limitation accumulation (+0.088 limitations per decade; 95% CI, 0.054–0.122; P < .001), approximately three times the excess associated with non-insulin treatment (+0.031; 95% CI, 0.014–0.049; P < .001). Associations increased across treatment levels, from no medication (+0.011; P = .49) to oral medication only (+0.039; P < .001) and insulin (+0.088). Insulin treatment was also associated with faster IADL limitation accumulation (+0.061 per decade; 95% CI, 0.032–0.090; P < .001). Findings were consistent across age groups (interaction P = .80). The insulin-associated excess ADL slope was smaller in 2010–2022 than in 1994–2008 (P < .001), but this difference was not observed when follow-up was restricted to 2010–2014 (P = .57). Conclusions: Higher diabetes treatment intensity, particularly insulin use, was associated with faster ADL and IADL limitation accumulation. Insulin-treated adults may benefit from proactive functional monitoring and coordinated care, although treatment intensity should not be interpreted as a causal determinant of decline.