Type I IDDM (insulin-dependent or juvenile onset) has a prevalence of 0.2-0.5% with males ==
females. The age of onset is usually <30 years. Genetically <10% of first-degree relatives are
affected with a 50% occurrence in identical twins.
Type II, or NIDDM (non-insulin-dependent or maturity onset) has a prevalence of 2-4%
with males> females. Patients are usually 40 years of age. Genetically >20% of
first-degree relatives are affected with 90-100% occurrence in identical twins.