Frequency of major affective disorders in first-degree relatives of patients with type 2 diabetes mellitus.

A genetic link between diabetes and depression has been proposed, but hardly explored. Data on family studies exploring relation between depression and diabetes are scanty. This study attempted to assess the prevalence of major affective disorders in first-degree relatives of patients with type 2 diabetes mellitus (T 2 DM).Fifty probands with T 2 DM, in whom other psychiatric disorders had been excluded, were chosen. Morbid risks and prevalence figures for depression and mania were estimated in 481 first-degree relatives of these 50 probands using the family interview for genetic studies.Of the 481 first-degree relatives of probands, only six had affective disorders. The morbid risk for depression in first-degree relatives was 2.99 and 3.87 per cent, assuming age of risk at 15-60 and 15-50 yr respectively, while the morbid risk for mania was 0.59 and 0.77 per cent in these age groups.The morbid risks/prevalence rates among first-degree relatives of probands with T2 DM were not higher than those of the general population rates derived from earlier Indian and western studies. This study did not demonstrate a family aggregation of affective disorders in patients with T 2 DM. Increased prevalence of affective disorders in diabetes could be due to non-genetic factors.