The prevalence of obesity is increasing globally in patients with diabetes. This study aimed to examine 12-year trends of increasing obesity in Japanese patients with diabetes, and their clinical features. The study used results of the Shiga Diabetes Clinical Survey, which recorded medical performance in diabetic patients in 2000, 2006 and 2012. Data were analyzed from 14,205, 14,407 and 21,449 adult patients in these three years, respectively. Overweight and obesity prevalence and the clinical features of diabetes patients were examined, stratified by body mass index (BMI) and age. The prevalence of overweight (BMI 25-30 kg/m2) and obesity (BMI ≥30 kg/m2) were 27.0% and 5.1% in 2000, 28.9% and 7.3% in 2006 and 30.9% and 10.0% in 2012. Glycemic control, blood pressure and serum lipid profile improved over 12 years in all BMI categories. However, glycemic and triglyceride control were insufficient in obese patients aged
