Objective: To examine the relationship between depressive symptoms and the incidence of type 2 diabetes.
Research design and methods: In 1984, 2,764 male employees of an electrical company in Japan completed a self-administered questionnaire including the Zung Self-Rating Depression Scale (SDS). They were followed for the next 8 years, and 2,380 (86%) responded to the follow-up survey in 1992. During the follow-up survey, occurrence of type 2 diabetes was diagnosed according to World Health Organization criteria.
Results: A total of 41 cases of type 2 diabetes were identified during the 8-year follow-up survey. After controlling for other known risk factors for type 2 diabetes, a proportional hazard analysis indicated that subjects who had moderate or severe levels of depressive symptoms (> or = 48 on the SDS) at baseline had a 2.3 times higher risk of having type 2 diabetes at the follow-up survey than those who were not depressed (< or = 39 on the SDS) (P < 0.05).
Conclusions: Depressive symptoms may be associated with the onset of type 2 diabetes.