Familial studies of type-I and type-II idiopathic diabetes mellitus.

A study of 296 diabetics demonstrated an association between the type of diabetes in the propositi and their first-degree relatives (aged 40 to 89 yr), the type of diabetes being defined as insulin-dependent (type I) or insulin-independent (type II). This association was significant at the 1% level and was still maintained when only the propositi in whom the diabetes was diagnosed at the age of 30 years or later were considered. The findings also suggest that there is a greater genetic independence between these two types than was previously supposed and that the disease should be subdivided into type according to the treatment needed rather than by the age of onset.