Diabetes mellitus in Kearns-Sayre syndrome.

A 20-year-old woman with Kearns-Sayre syndrome (KSS) suddenly experienced two episodes of diabetic coma. She was studied to determine whether diabetes mellitus (DM) resulted from insulin resistance or from an insulin secretion abnormality, using the euglycemic glucose clamp technique and the glucagon tolerance test. She had a deficiency of insulin secretion from beta cells. It is important to recognize in practice the onset of DM in patients with mitochondrial myopathy. We would suggest that a genetic linkage or mitochondrial dysfunction may be responsible for the association of both disease states.