The Association between Type of Work and Insulin Resistance and the Metabolic Syndrome in Middle-Aged Korean Men: Results from the Korean National Health and Nutrition Examination Survey IV (2007~2009)

PURPOSE Type of work might be related to insulin resistance and the metabolic syndrome (MetS). However, scant data are available. We performed this study to investigate whether the prevalence of MetS and insulin resistance differed according to occupation in middle-aged men. MATERIALS AND METHODS In all, 2,348 men in their 40s~50s who had participated in the Korean National Health and Nutrition Examination Survey IV were included and were classified into two groups according to the type of work (manual worker vs. non-manual worker). Diagnosis of MetS required satisfying three or more of the National Cholesterol Education Program-Adult Treatment Panel III criteria. Fasting insulin, the glucose/insulin ratio (G/I ratio), and the homeostasis model assessment of insulin resistance (HOMA-IR) were used to estimate the insulin resistance. We used the Mann-Whitney test, χ(2) tests, multiple linear regression test, and logistic regression analyses to examine the relationships. RESULTS Age was significantly higher in the manual worker group. Body mass index was significantly lower in the manual worker group. Rates of current smoking and frequent drinking were higher in the manual worker group. In terms of surrogate markers of insulin resistance, the age-adjusted mean of fasting insulin, G/I ratio, and HOMA-IR indicated that lower insulin resistance was significantly related to manual work. After adjusting for age and other confounding factors, non-manual workers had a higher risk of the MetS than manual workers. The odds ratio in relation to MetS was significantly lower in the manual workers. CONCLUSIONS MetS and impaired insulin resistance are significantly related to non-manual work in middle-aged Korean men.