OBJECTIVE: To compare the risk of developing diabetes mellitus (DM) in the general population between subjects who had a depression and subjects who never had a depression. METHOD: Retrospective cohort design. People with depression were diagnosed with a depression between 1975 and 1990; controls never had a depression. Both groups were followed for a diagnosis of type II diabetes until 2000. Data on 1334 depressed and 66 670 non-depressed subjects were available from a large general practice-based database. RESULTS: No overall relation was found, but among males below age 50 there was a 78% increase in the rate of development of DM compared with non-depressed patients (hazard ratio 1.78, 95% CI: 1.21-2.62). CONCLUSION: Depression in males between the age of 20 and 50 years is related to an increased risk of developing DM.