Clinical aspects of mitochondrial diabetes.

Mitochondrial diabetes is a new nosological entity, the most common form of which is maternally inherited diabetes and deafness (MIDD) syndrome. In this syndrome, delayed insulin dependency is frequently observed, although any form of glucose intolerance is possible. The mechanism of diabetes is localised at the beta-cell level. The participation of an autoimmune process in beta-cell loss is still controversial. An association with macular pattern dystrophy and infraclinical myopathy is common and can facilitate diagnosis. Muscle 31-P MR spectroscopy is a non-invasive tool to detect oxidative and phosphorylative alterations and monitor the reversion of these anomalies through specific treatments. Numerous other mutations, deletions or duplications of mtDNA have been associated with diabetes. The description of mitochondrial diabetes is still in progress. In future, an understanding of the mechanism of glucose intolerance in these diseases should open the way to specific preventive treatments in subjects carrying diabetogeneic mutations of mtDNA.