2019 Volume 62 Issue 3 Pages 162-169
A 43-year-old deaf woman who presented with headache and nausea was referred to our department to undergo treatment for diabetic ketoacidosis. She needed basal-bolus insulin treatment because her insulin secretory reserve was severely reduced. Mitochondrial diabetes mellitus (MDM) was suspect based on her sensorineural deafness and a maternal family history of diabetes. Because a mitochondrial DNA 3243 A>G mutation was detected in her blood leukocytes, she was diagnosed with MDM. Although there was no evidence of diabetic microangiopathy, she exhibited atrophy of both the occipital lobe of the cerebrum and cerebellum associated with an m.3243A>G mutation. Her 41-year-old younger sister was also deaf and was previously diagnosed with diabetes. The younger sister's treatment course differed in that she was treated with oral glucose-lowering agents. She also had an m.3243A>G mutation and was diagnosed with MDM. Her manifestations were differed from her sister's in that she had renal dysfunction and cardiomyopathy. The clinical manifestations in patients with mitochondrial disease vary because heteroplasmy levels of m.3243A>G mutation are divergent in organs and tissues. We report sibling cases of MDM that presented with distinct clinical manifestations.