Metabolic syndrome and its components among Korean submariners: a retrospective cross-sectional study

Metabolic syndrome (MetS) is a cluster of inter-related risk factors for cardiovascular disease and diabetes. Although submariners tend to be exposed to unhealthy environmental factors, such as a confined work environment, physical inactivity, and circadian disruption, little is known regarding whether the risks of MetS and its components are associated with submarine service. The present study aimed to evaluate the risks of MetS and its components among submariners. A total of 5090 subjects (513 submariners and 4577 non-submariners) were included in the present study. We calculated the age-standardized and age-specific prevalences of MetS. The associations between submarine service and the risks of MetS and its components were evaluated using logistic regression analysis after adjusting for age, service rank, and lifestyle factors. The age-standardized prevalences of MetS were 17.6 and 15.1% among submariners and non-submariners, respectively. Compared to non-submariners, submariners had higher risks of MetS (odds ratio [OR] 1.31, 95% confidence interval [CI] 1.02, 1.68), low high-density lipoprotein cholesterol (OR 1.73, 95% CI 1.36, 2.20), and impaired fasting glucose (OR 1.46, 95% CI 1.21, 1.76). When we stratified the subjects according to physical activity, an increased risk of elevated blood pressure associated with submarine service was evident only in the subgroup with moderate or vigorous physical activity (P for interaction = 0.006). Submariners had higher risks of MetS and some MetS components, compared to non-submariners. These findings suggest that special efforts are needed to prevent and manage MetS among individuals who are expected to be exposed to submarine environment.