Aims/hypothesis: The aim of this study was to characterise longitudinal profiles of BMI from childhood and to examine the impact of level-independent childhood BMI trajectories on adult type 2 diabetes.
Methods: The longitudinal cohort consisted of 2449 adults (1613 white and 836 black) who had their BMI measured between four and 15 times from childhood (4-19 years) to adulthood (20-51 years) and fasting glucose measured in adulthood. Model-estimated levels and linear slopes of BMI at childhood age points were calculated in 1-year intervals using growth-curve parameters and their first derivatives, respectively.
Results: BMI from childhood to adulthood fit cubic growth curves; linear and non-linear curve parameters differed significantly between race-sex groups. BMI showed race and sex differences from 15 years onwards. Individuals with hyperglycaemia had higher long-term BMI levels than those who were normoglycaemic in race-sex groups. Linear and non-linear slope parameters of BMI differed consistently and significantly between adult hyperglycaemia groups. The OR of childhood BMI levels for ages 4-19 years was 1.45-1.83 (p < 0.001 for all) for adult hyperglycaemia after adjustment for confounders. Level-adjusted linear slopes of BMI at ages 10-19 years showed significantly positive associations with adult hyperglycaemia (OR 1.17-1.50, p < 0.01 for all). The associations of childhood BMI linear slopes with adult hyperglycaemia were not significant during the age period 5-9 years. The trends in these associations were consistent across race-sex groups.
Conclusions/interpretation: These observations indicate that childhood BMI trajectories have a significant impact on adult diabetes, independent of BMI levels. The adolescence age period is a crucial window for the development of diabetes in later life, which has implications for early-life prevention.
Data availability: All data and materials are publicly available at the National Heart, Lung, and Blood Institute (NHLBI) Biologic Specimen and Data Repository and can be accessed at https://biolincc.nhlbi.nih.gov/studies/bhs .
Keywords: Body mass index; Childhood; Diabetes; Hyperglycaemia; Longitudinal study.