Clinical and etiological heterogeneity of idiopathic diabetes mellitus. The banting memorial lecture.

We have presented and reviewed evidence for the heterogeneous nature of diabetes mellitus in terms of genetics, environmental factors, insulin responses to glucose and vascular disease. We have reviewed evidence for heterogeneity between juvenile-onset diabetes (JOD) and maturity-onset diabetes (MOD) and maturity-onset diabetes of young (MODY) and for heterogeneity within groups of JOD and MOD and MODY patients. Although much remains to be learned, a beginning has been made and suggests that primary diabetes mellitus is not a single specific disease but a syndrome comprised of a variety of diseases all characterized by hyperglycemia and tissue changes that result from heterogeneous etiologic and pathogenetic factors. Future classifications of primary diabetes mellitus will undoubtedly be lengthy, as are for other diseases and syndromes also caused by a variety of etiologic and pathogenetic mechanisms.