BMI Trajectories in Late Middle Age, Genetic Risk, and Incident Diabetes in Older Adults: Evidence From a 26-Year Longitudinal Study

This study investigated the association between body mass index (BMI) trajectories in late middle age and incident diabetes in later years. A total of 11,441 participants aged 50-60 years from the Health and Retirement Study with at least 2 self-reported BMI records were included. Individual BMI trajectories representing average BMI changes per year were generated using multilevel modeling. Adjusted risk ratios (ARRs) and 95% confidence intervals (95% CIs) were calculated. Associations between BMI trajectories and diabetes risk in participants with different genetic risks were estimated for 5,720 participants of European ancestry. BMI trajectories were significantly associated with diabetes risk in older age (slowly increasing vs. stable: ARR = 1.31, 95% CI: 1.12, 1.54; rapidly increasing vs. stable: ARR = 1.5, 95% CI: 1.25, 1.79). This association was strongest for normal-initial-BMI participants (slowly increasing: ARR = 1.34, 95% CI: 0.96, 1.88; rapidly increasing: ARR = 2.06, 95% CI: 1.37, 3.11). Participants with a higher genetic liability to diabetes and a rapidly increasing BMI trajectory had the highest risk for diabetes (ARR = 2.15, 95% CI: 1.67, 2.76). These findings confirmed that BMI is the leading risk factor for diabetes and that although the normal BMI group has the lowest incidence rate for diabetes, people with normal BMI are most sensitive to changes in BMI.