The familial aggregation of the DN demonstrates the involvement of genetic factors in the pathogenesis of this complication, and available data provide convincing evidence that the angiotensin converting enzyme I/D (ACE I/D) polymorphism is significantly associated with overt nephropathy being the insertion/insertion (II) genotype and low plasma ACE levels protective against the disease both in type I and type II diabetics [17–19]. The gene discussed is ACE; the disease is kidney disorder.