Association between variability in body mass index and development of type 2 diabetes: Panasonic cohort study

INTRODUCTION: Contrasting results have been reported for the association between the variability in body weight and development of diabetes. In the present study, we evaluated the association between the variability in body mass index (BMI) and development of type 2 diabetes in 19 412 Japanese participants without obesity and without body weight gain or loss during the study period. RESEARCH DESIGN AND METHODS: We recorded body weight of the participants consecutively each year in Panasonic Corporation, Osaka, Japan from 2008 to 2014 to evaluate the variability of BMI. The participants with obesity (BMI ≥25 kg/m(2)) at baseline and body weight gain or loss from 2008 to 2014 (delta BMI ≥±1 kg/m(2)) were excluded from the study. In total, 416 participants developed type 2 diabetes from 2015 to 2018. We used coefficient of variation (CV) to represent the variability in BMI during 6 years of the study period. RESULTS: Cox regression analyses revealed that the risk of developing type 2 diabetes was higher in the fourth quartile (HR 1.33; 95% CI 1.01 to 1.75) of CV of BMI than that in the first quartile (lowest quartile) of CV of BMI after adjusting for multiple confounding factors. The risk for developing diabetes increased by 11.1% per 1% increase in CV of BMI. CONCLUSIONS: In conclusion, the variability in BMI is a risk factor for the development of diabetes in the Japanese population without obesity and without body weight gain or loss.