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Objective: To investigate associations of work-related stressors and their changes over time with the risk of developing metabolic syndrome (MetS) among Japanese manufacturing workers., Methods: Participants were 1,040 employees aged 19 to 68 years who were free from MetS at baseline and completed the three year-interval follow-up survey. MetS was defined according to the Joint Interim Statement. Work-related stressors (job strain, job demands, job control, and worksite social support) were assessed based on the Job Content Questionnaire and were split into two categories (low and high) by the median value at each survey. Multivariable logistic regression was performed to investigate the associations of baseline work-related stressors and their changes over time with the incidence of MetS., Results: Three years later, 61 workers developed MetS. Higher job demands at baseline were significantly associated with a lower risk of MetS (adjusted odds ratio 0.46, 95% confidential interval: 0.24, 0.89). In the analyses of the changes in stressors over time, those whose job demands changed from low to high showed significantly higher risk of MetS (adjusted odds ratio 3.27, 95% confidential interval: 1.46, 7.34), compared with those who reported low job demands in both surveys., Conclusions: Results suggest that an increase in job demands over time, but not higher job demands at baseline, is associated with increased risk of MetS.

Background: We investigated the risk of cardiovascular disease (CVD) with duration of metabolic syndrome (MetS) for the past 4 years before the CVD event., Methods and results: We performed a nested case-control study within the Japan Epidemiology Collaboration on Occupational Health Study. A total of 139 registered cases of CVD and 561 self-reported cases of CVD were identified and matched individually on age, sex, and worksite with 695 and 2,803 controls, respectively. MetS was defined by the Joint Interim Statement definition. The odds ratio (95% confidence interval) for registered CVD was 4.7 (2.9, 7.5) for people with persistent MetS (positive for MetS for ≥3 assessments) and 1.9 (1.1, 3.3) for those with intermittent MetS (positive for MetS for 1-2 assessments), compared with people without MetS during the past 4 years before the event/index date (P for trend <0.001). The corresponding odds ratio for self-reported CVD was 2.7 (2.2, 3.5) and 1.8 (1.4, 2.3) (P for trend <0.001). The association with MetS duration was stronger for myocardial infarction than for other CVD subtypes. Similar results were obtained when using the Japanese MetS criteria., Conclusions: The risk of CVD increases with increasing MetS duration. These findings contribute to risk stratification and encourage lifestyle modification for people with MetS to minimize their health risk.

Background: We prospectively examined the association of diabetes risk with the number of metabolic abnormalities, as well as their combinations, according to the presence or absence of impaired fasting glucose (IFG) in a large-scale Japanese working population., Methods: Participants included 55,271 workers at 11 companies who received periodic health check-ups between 2008 and 2013. The metabolic syndrome (MetS) components were defined using the 2009 Joint Interim Statement. IFG was defined as fasting plasma glucose 5.6-6.9 mmol/L. Diabetes newly diagnosed after the baseline examination was defined according to the American Diabetes Association criteria. We calculated the hazard ratios (HRs) for diabetes incidence using the Cox proportional hazards model., Results: During the follow-up period (median 4.95 years), 3183 subjects developed diabetes. In individuals with normal fasting glucose levels, the risk of diabetes increased steadily with the increasing number of MetS components; the multivariable-adjusted HRs for incident diabetes for the number of MetS components were 2.0, 4.3, 7.0, and 10.0 for one, two, three, or four MetS components, respectively, compared with the absence of components. A similar association was observed among individuals with IFG; the corresponding HRs were 17.6, 23.8, 33.9, and 40.7. The combinations that included central obesity appeared to be more strongly associated with diabetes risk than other combinations with the same number of MetS components within the same glucose status., Conclusions: Our findings indicate that risk stratification of individuals by the presence or absence of IFG and the number of MetS components can detect individuals with a high risk of diabetes., (Copyright © 2017 The Authors. Production and hosting by Elsevier B.V. All rights reserved.)

Objective: Increasing evidence has suggested a protective role of vitamin D on metabolic syndrome (MetS). However, studies addressing this issue are limited in Asia and it remains unclear whether calcium could modify the association. We examined the association of serum 25-hydroxyvitamin D (25(OH)D) status with MetS, and the potential effect modification by calcium intake in a Japanese working population., Methods: Study subjects were 1790 workers, ages 18 to 69 y, who participated in a health survey at the time of periodic checkup. MetS was defined according to the joint interim statement. Serum 25(OH)D was measured by a protein binding assay. Multilevel logistic regression was used to estimate the odds ratio (OR) with adjustment for potential confounding variables., Results: An inverse trend was observed between 25(OH)D and MetS. Compared with those with a 25(OH)D of <20 ng/mL, multivariable adjusted OR (95% confidence interval) for MetS was 0.79 (0.55-1.15) and 0.52 (0.25-1.04) for those with a 25(OH)D of 20 to 29 ng/mL and ≥30 ng/mL, respectively (P for trend = 0.051). Similar association was observed in the analysis using quartile categories of 25(OH)D; the OR in the highest quartile of 25(OH)D compared with the lowest quartile was 0.61 (0.36-1.01) (P for trend = 0.046). This association was noted only in older subjects (≥44 y). The inverse association between serum 25(OH)D and MetS was more pronounced in subjects with high calcium intake. The inverse association between 25(OH)D and MetS appears to be linear according to restricted cubic spline regression. There was inverse, but statistically nonsignificant, associations between 25(OH)D and each component of MetS., Conclusion: Our results suggest that higher circulating vitamin D is associated with decreased likelihood of having MetS among Japanese adults., (Copyright © 2016 Elsevier Inc. All rights reserved.)

Background: We sought to establish the optimal waist circumference (WC) cut-off point for predicting diabetes mellitus (DM) and to compare the predictive ability of the metabolic syndrome (MetS) criteria of the Joint Interim Statement (JIS) and the Japanese Committee of the Criteria for MetS (JCCMS) for DM in Japanese., Methods: Participants of the Japan Epidemiology Collaboration on Occupational Health Study, who were aged 20-69 years and free of DM at baseline (n = 54,980), were followed-up for a maximum of 6 years. Time-dependent receiver operating characteristic analysis was used to determine the optimal cut-off points of WC for predicting DM. Time-dependent sensitivity, specificity, and positive and negative predictive values for the prediction of DM were compared between the JIS and JCCMS MetS criteria., Results: During 234,926 person-years of follow-up, 3180 individuals developed DM. Receiver operating characteristic analysis suggested that the most suitable cut-off point of WC for predicting incident DM was 85 cm for men and 80 cm for women. MetS was associated with 3-4 times increased hazard for developing DM in men and 7-9 times in women. Of the MetS criteria tested, the JIS criteria using our proposed WC cut-off points (85 cm for men and 80 cm for women) had the highest sensitivity (54.5 % for men and 43.5 % for women) for predicting DM. The sensitivity and specificity of the JCCMS MetS criteria were ~37.7 and 98.9 %, respectively., Conclusion: Data from the present large cohort of workers suggest that WC cut-offs of 85 cm for men and 80 cm for women may be appropriate for predicting DM for Japanese. The JIS criteria can detect more people who later develop DM than does the JCCMS criteria.