The causal role of obesity in diabetic kidney disease —evidence from a Mendelian randomization study

Whether obesity is a direct cause of diabetic kidney disease (DKD) is unclear. Using a Mendelian randomization approach, Todd and colleagues assessed the association between BMI and DKD in 6,049 patients with type 1 diabetes mellitus, before comparing these data with results from cross-sectional and longitudinal observations. In the cross-sectional analysis, no association was seen between BMI and overall DKD. However, in the Mendelian randomization analysis, every 1 kg/m² increase in BMI was associated with an increased risk of developing DKD. Although supporting a causal role for obesity in the development of DKD, the investigators highlight that these data do not reveal the underlying mechanism of this association.