Longer exposure to obesity and earlier development of obesity to increased risk of type 2 diabetes

Cumulative exposure to obesity could be at least as important as actually being obese in terms of risk of developing type 2 diabetes (T2D), concludes new research published in the journal Diabetologia. The study is by Dr Juhua Luo, School of Public Health, Indiana University, Bloomington, IN, USA, and colleagues.

Although obesity is a well-established risk factor for T2D, little is known about the relationships between age of onset of obesity and cumulative exposure to obesity and risk of T2D, especially among young adults. In this study, the authors examined the relationship between distinct BMI trajectories and risk of T2D. Also investigated were the associations between timing of obesity onset, obese-years and T2D.

Higher initial BMI was associated with an increased risk of diabetes. Increased age at onset of obesity was associated with a lower risk of diabetes, with a 13% lower risk of developing T2D per one-year delay in onset. A higher number of obese-years was associated with increased risk of developing T2D. Obese years is calculated by person's BMI minus the BMI for obesity (30), then multiplying by the number of years of exposure. The authors estimate* that for each extra 10-obese years, the risk of diabetes increased by 25%.