Trajectories of body mass index and diabetes mellitus risk among elderly Chinese adults: A 10‐year longitudinal study

This study aimed to identify trajectories of body mass index (BMI) for elderly Chinese adults, evaluate the impact of BMI trajectories on the risk of diabetes mellitus (DM) or impaired fasting glucose (IFG) among normoglycaemic elderly and compare the incidence of progression to DM and reversion to normoglycaemia between BMI trajectories among IFG elderly to prevent the occurrence of diabetes. This study included 148 970 participants. Group-based trajectory modelling was used to identify BMI trajectories. Cox proportional hazards regression models were used to examine the associations between BMI trajectories and the incidence of DM, IFG and reversion to normoglycaemia. A total of six patterns of trajectory were identified: minor decrease, sharply decrease, stable, slight increase, moderate increase and significant increase among 148 970 elderly Chinese adults. For normoglycaemic elderly, compared with normal weight-stable trajectory, the trajectories with higher DM risk are the obese-pronounced decrease group, the obese-marginal increase group, and the obese-minor decrease group. The adjusted hazard ratios (HRs) were: 2.70 (95% confidence interval [CI]: 2.35, 3.11), 2.55 (95% CI: 2.28, 2.86) and 2.41 (95% CI: 2.24, 2.60), respectively. The trajectories with higher IFG risk are the obese-marginal increase group, the obese-minor decrease group and the overweight-moderate increase group, with adjusted HRs of 2.26 (95% CI: 2.08, 2.45), 1.96 (95% CI: 1.86, 2.07) and 1.91 (95% CI: 1.79, 2.04), respectively. Among 148 970 participants, normoglycaemic elderly with increased BMI trajectories showed elevated DM and IFG risks in groups with underweight and normal weight. Regardless of the BMI trajectory, the risk of DM was increased in both the obese and overweight groups. For IFG elderly, the highest DM incidence was presented in the decreasing trajectories.