A subtype of diabetes mellitus associated with a mutation of mitochondrial DNA

A mutation of mitochondrial DNA may be associated with both insulin-dependent diabetes (IDDM) and non-insulin-dependent diabetes (NIDDM). Mitochondrial DNA is the genetic material associated with the energy-producing compartments of cells. Researchers in Japan identified a particular mitochondrial DNA mutation in three of 55 (6%) patients with IDDM and a history of diabetes in first-degree relatives, in two of 100 (2%) patients with NIDDM and a history of diabetes in first-degree relatives, in three of five (60%) patients with diabetes and hearing loss and in eight of 39 (21%) patients with a syndrome consisting of mitochondrial muscle disease, degenerative brain disease, accumulation of lactic acid and stroke-like episodes. The mutation was also found in 62 relatives of the patients studied. The mutation was not found in 85 patients with IDDM who had no family history of diabetes or in 200 healthy persons with no family history of diabetes. The mutation may cause some cases of both IDDM and NIDDM in Japan, and it appears to be inherited from a mother with diabetes.