Objective: To examine whether job strain is associated with an increased risk of subsequent Type 2 diabetes mellitus (T2DM) development in a population-based study of men and women.
Methods: Data were derived from the prospective MONICA/KORA Augsburg study. We investigated 5337 working participants aged 29 to 66 years without diabetes at one of the three baseline surveys. Job strain was measured by the Karasek job content questionnaire. High job strain was defined by the quadrant approach, where high job demands combined with low job control were classified as high job strain. Continuous job strain (quotient of job demands divided by job control) was additionally analyzed as sensitivity analysis. Hazard ratios (HRs) were estimated using multivariable Cox proportional hazards models with adjustment for age, sex, survey, socioeconomic and life-style variables, parental history of diabetes, and body mass index.
Results: During a median follow-up of 12.7 years, 291 incident cases of T2DM were observed. The participants with high job strain at baseline had a 45% higher fully adjusted risk to develop T2DM than did those with low job strain (HR = 1.45 [95% confidence interval = 1.00–2.10], p = .048). On the continuous scale, more severe job strain in the magnitude of 1 standard deviation corresponded to a 12% increased fully adjusted T2DM risk (HR = 1.12 [95% confidence interval = 1.00–1.25], p = .045).
Conclusions: Men and women who experience high job strain are at higher risk for developing T2DM independently of traditional risk factors. Preventive strategies to combat the globally increasing T2DM epidemic should take into consideration the adverse effects of high strain in the work environment.
From the Institute of Epidemiology II (C.H., B.T., J.B., R.T.E., A.S., C.M., K.-H.L), Helmholtz Zentrum München, German Research Center for Environmental Health (GmbH), Helmholtz Zentrum München, Neuherberg, Germany; German Center for Diabetes Research (DZD) (C.H., B.T., A.S., C.M.), Neuherberg, Germany; Department of Psychosomatic Medicine and Psychotherapy (J.K.), University of Gießen, Gießen, Germany; Department of Psychosomatic Medicine and Psychotherapy (J.K.), University of Marburg, Marburg, Germany; MONICA/KORA Myocardial Infarction Registry (C.M.), Central Hospital of Augsburg, Augsburg, Germany; and Department of Psychosomatic Medicine and Psychotherapy (K.-H.L.), Klinikum Rechts der Isar, Technische Universität München (TUM), Munich, Germany.
Address correspondence and reprint requests to Karl-Heinz Ladwig, PhD, MD, Institute of Epidemiology II, Helmholtz Zentrum München, German Research Center for Environmental Health, Ingolstädter Landstr. 1, 85764 Neuherberg, Germany. E-mail: email@example.com
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Received for publication August 22, 2013; revision received May 2, 2014.