Maximum BMI and microvascular complications in a cohort of Japanese patients with type 2 diabetes: the Japan Diabetes Complications Study

AimsThe aim of this study was to examine the associations between possible indices of obesity based on information on weight history and the incidence of microvascular complications.MethodsA cohort of individuals with type 2 diabetes from 59 institutes in Japan was followed for 8 years. Patients were classified into three categories according to weight at entrance and past maximum weight: normal (BMI at baseline < 25 kg/m2 and maximum BMI < 25 kg/m2), past obesity (BMI at baseline < 25 kg/m2 and maximum BMI ≥ 25 kg/m2), and current obesity (BMI at baseline ≥ 25 kg/m2) groups. The outcomes were diabetic retinopathy and overt nephropathy.ResultsBMI at maximum and baseline of the 1809 patients was 26.5 ± 3.5 and 23.1 ± 3.0 kg/m2 (p < 0.01), respectively (23.0 ± 1.6 and 20.6 ± 1.9 kg/m2 for normal, 27.4 ± 2.0 and 22.8 ± 1.4 kg/m2 for past obesity, and 30.1 ± 2.9 and 27.0 ± 1.8 kg/m2 for current obesity). The hazard ratios of past and current obesity compared to normal were 1.92 (95% CI, 1.08–3.41; p = 0.03) and 2.21 (1.16–4.22; p = 0.02), respectively, for overt nephropathy and 1.38 (1.05–1.83; p = 0.02) and 1.64 (1.18–2.28; p < 0.01), respectively, for diabetic retinopathy after adjustment for confounders.ConclusionsPast obesity as well as current obesity were associated with increased risks of microvascular complications. Further identification of high-risk populations may be possible by classifying normal weight patients by past obesity.