Time-trends in body mass index, and overweight and obesity as independent risk factors for diabetes angiopathy in young females with type 1 diabetes : A nationwide study in Sweden

Aims: To examine time-trends in BMI-distributions of young females with and without type 1 diabetes (T1D), with focus on the upper half of the distribution i.e., the median and above, and to explore if overweight and obesity independently increase risk of diabetes angiopathy. Methods: Population-based cohort study of 3,473 females with T1D, 16-35 years, identified in the Swedish National Diabetes Registers, January 2005 to October 2015, and 8,487 females from the background population. BMI-distributions were examined using kernel density estimates and quantile regression. Hazard ratios (HRs) and 95 % confidence intervals (CIs) for angiopathy in overweight/obese subjects were estimated with adjusted Cox regression. Results: The BMI-distribution in females with T1D was right shifted to that of the background population (p < 0.001). The 90th percentile and median BMI increased equally overtime in both groups, but females with T1D started from a higher baseline. In T1D, HRs were significantly increased for any angiopathy in individuals with obesity (adj HR 1.37 (CI 1.14-1.64)), and for retinopathy; adj HRs (CIs): overweight; 1.15 (1.02-1.29), obesity; 1.30 (1.08-1.56). Conclusions: Females with T1D have increasing BMI overtime and are heavier than females without T1D. Overweight and obesity are by themselves risk factors for angiopathy