Objective Increased weight gain has been reported prior to disease onset (accelerator hypothesis) and as a side effect of intensified insulin therapy in type 1 diabetes (T1D). Paediatric studies are complicated by the age-dependency and gender-dependency of BMI, and also by a trend towards obesity in the general population. The aim of this study was to evaluate factors related to the increase in BMI during the course of diabetes in children and adolescents with T1D in a large multicentre survey.

Design Within the DPV database (Diabetespatienten Verlaufsdokumentation) a standardised, prospective, computer-based documentation programme, data of 53 108 patients with T1D, aged <20 years, were recorded in 248 centres. 12 774 patients (53% male, mean age 13.4±3.9, mean diabetes duration 4.7±3.0 years and mean age at diabetes onset 8.7±4.0 years) were included in this analysis. Population-based German reference data were used to calculate BMI-SDS and define overweight and obesity.

Results 12.5% of T1D patients were overweight and 2.8% were obese. Multiple longitudinal regression analysis revealed that female gender, low BMI at diabetes onset, intensified insulin therapy and higher insulin dose, as well as pubertal diabetes onset, long diabetes duration and onset in earlier calendar years among girls, were related to higher BMI-SDS increase during the course of diabetes (p<0.01; all).

Conclusions Intensified insulin regimen is associated with weight gain during T1D treatment, in addition to demographic variables. Optimisation of diabetes management, especially in females, might limit weight gain in order to reduce overweight and obesity together with comorbidities among paediatric T1D patients.