Abstract P231: Cumulative Body Mass Index and Incident Prediabetes Over 30 Years of Follow Up: The Coronary Artery Risk Development in Young Adults (CARDIA) Study

Abstract

Introduction: Higher body mass index (BMI) is associated with incident prediabetes, but whether the association is related to higher BMI or duration is unclear. Methods: We examined cumulative BMI (cBMI) in 4227 black and white men and women, ages 18-30 years at baseline, who were free of prediabetes and diabetes at baseline and did not transition directly from normoglycemia to diabetes. cBMI was a time-varying measure defined as the BMI at a given study visit multiplied by the time until the next available BMI measurement, summed across exams. Prediabetes was defined as fasting glucose of 100-125 mg/dL, 2-hour oral glucose tolerance of 140-199 mg/dL, or HbA1c of 5.7-6.4%. Proportional hazards regression was used to estimate hazard ratios for incident prediabetes across tertiles of cBMI over a maximum of 30 years, without and with adjustment for lifestyle and demographic variables. Results: Over an average of 20.4 years of follow up (range 7 to 30 years), there were 2406 incident prediabetes events (56.9% of the sample). Incident events were observed in each cBMI tertile across the full range of follow-up time. In crude models (Table), the hazard ratios for the second and third tertiles of cBMI were statistically significantly and positively associated with incident prediabetes relative to the first tertile. Multivariable adjustment attenuated the associations such that only the third cBMI tertile remained statistically significant, with an 83% higher rate of prediabetes compared to those in the first tertile. These associations did not differ by race, sex or age. Conclusions: Cumulative BMI, a measure capturing both BMI level and duration, was strongly associated with prediabetes only when a relatively high threshold was reached. These results suggest that a high cumulative burden over a wide range of BMI values and persistence from young adulthood is associated with prediabetes by middle age, allowing primary prevention before middle age and progression to frank diabetes.