Depressive symptoms and the risk of type 2 diabetes mellitus in a US sample

Objective. There is some evidence to suggest that individuals with depression are at an almost twofold increased risk of developing type 2 diabetes mellitus, but results are far from conclusive. Therefore, to determine if depressive symptoms increased the risk of type 2 diabetes, we conducted longitudinal analyses using data from the NHANES I Epidemiologic Follow-up Survey (NHEFS). Research design and methods. Participants included individuals who were white or African-American, did not report previous diagnosis of diabetes, and who completed the Centers for Epidemiologic Studies Depression (CES-D) questionnaire in the 1982-1984 study (n = 8870). Participants were followed up for incident-diagnosed diabetes through 1992 (mean follow-up 9.0 years). Results. There were 1444 (15.9%) participants with high depressive symptoms in the 1982-1984 study (CES-D score ≥ 16). During follow-up, there were 465 incident cases of diabetes. Incidence of diabetes was 6.9/1000 person years among those with high depressive symptoms, 6.0/1000 person years among those with moderate symptoms, and 5.0/1000 person years among those with no symptoms. After adjusting for age, sex, and race, the relative hazard (RH) of diabetes among those with high depressive symptoms was 1.27 (95% CI: 0.93 to 1.73) compared to those without symptoms. Further adjustment for education and known diabetes risk factors (body mass index and physical activity) further attenuated the relationship (RH 1.11, 95% CI: 0.79 to 1.56). Conclusions. There was no increased incidence of diabetes for those with high or moderate depressive symptoms compared to those with no depressive symptoms. These results do not support the etiologic relationship of depression predisposing individuals to diabetes.