Abstract
AIMS/INTRODUCTION: We investigated the risk of incident type 2 diabetes according to the cumulative exposure to obesity or metabolic syndrome (MetS) during annual or biennial health examinations. MATERIALS AND METHODS: The Korean National Health Insurance Service datasets from 2002 to 2017 were used for this retrospective longitudinal study. The risk for type 2 diabetes was analyzed according to the cumulative exposure to obesity and MetS among individuals who underwent four health examinations from 2009 to 2012 or 2013 (n = 2,851,745). RESULTS: During examinations, 28.56 and 17.86% of the total participants showed fluctuations in metabolic health state and obesity, respectively. During a mean 5.01 years of follow up, 98,950 new type 2 diabetes cases developed. The risk for type 2 diabetes increased with the increase in exposure to MetS (hazard ratio [HR] 2.92, 95% confidence interval [CI] 2.86-2.99; HR 4.96, 95% CI 4.85-5.08; HR 7.46, 95% CI 7.30-7.63; HR 12.24, 95% CI 12.00-12.49 in groups with number of exposures one to four, respectively) and obesity (HR 1.60, 95% CI 1.56-1.65; HR 1.87, 95% CI 1.81-1.92; HR 2.25, 95% CI 2.19-2.31; HR 3.46, 95% CI 3.41-3.51 in groups with number of exposures one to four, respectively), showing a more detrimental effect of cumulative exposure to MetS, when compared with the exposure to obesity. CONCLUSIONS: Metabolic health and obesity fluctuated within a relatively short period of 4-5 years. Although the impact was much greater for MetS than for obesity, the cumulative duration of both obesity and MetS was associated with an increased risk of type 2 diabetes in a dose-response manner. Therefore, continuously maintaining metabolic health and normal weight is crucial to prevent incident type 2 diabetes.