Abstract
INTRODUCTION: Sex is a critical predictor of body mass index (BMI) trajectory over the life span, playing a role in disparities in the risk of diabetes. While there is some evidence of the effect of BMI on the risk of diabetes, little is known about sex differences in BMI trajectories over the life span and their later life association with diabetes, especially in low-income and middle-income settings. METHODS: Using panel data from the Indonesian Family Life Survey, this study examines the impact of an individual's BMI trajectory throughout adulthood on diabetes onset. Analysis for men and women were conducted separately. First, growth curve modelling estimates individuals' BMI trajectories over age. Second, the effect of BMI trajectories on diabetes is estimated using logistic regression adjusted for individual socioeconomic status. Finally, we perform relative dominance analysis to test the importance of BMI trajectories as a predictor of diabetes in later life against abdominal obesity measurements. RESULTS: BMI trajectories over adulthood strongly predict the probability of diabetes in both men and women. A rapidly increasing BMI significantly increases the probability of diabetes in men regardless of individuals' initial BMI. Among women, those who started out with an overweight/obese BMI and experienced a rapid loss in BMI over age had the highest risk of diabetes. Greater educational attainment is associated with an increase in the likelihood of diabetes in men, but higher education level is a protective factor from diabetes in women. CONCLUSION: The findings suggest that maintaining BMI at normal cut-off over the life course can lower the likelihood of diabetes onset in later adulthood. This study emphasises that simple monitoring of BMI trajectory over adulthood could be a useful tool to identify the population at risk of diabetes in contexts with substantial underdiagnoses of diabetes.