To compare the lifetime prevalence of mood disorders among those with and without type 1 diabetes.Data from a nationally representative sample were obtained. Individuals were classified as having type 1 diabetes if a health professional diagnosed them with diabetes before age 30 and they began insulin within 1 month of their diagnosis (N=314).The prevalence of mood disorders in persons with type 1 diabetes was 7.9% (95% CI 3.1–12.7) compared to 5.6% (95% CI 5.4–5.8) for those without type 1 diabetes (age- and sex-adjusted OR=1.56, 95% CI 1.04–2.34).Future research would benefit from the use of community-based representative samples.