A Case of Mitochondrial Diabetes Mellitus with Various Autonomic Symptoms and Subclinical Cardiac Dysfunction

We report the case of a 48 year-old woman. At the age of 38 years, she was diagnosed as having diabetes mellitus. Three years later, she became aware of orthostatic hypotension, residual urine and palpitations, but there were no abnormal findings on routine tests. Subsequently, a 3243 mitochondrial tRNA (leu) mutation was documented in her leukocytes, and myocardial imaging using ¹²³I-labeled beta-methyl-iodophenyl pentadecansic acid (₁₂₃I-BMIPP) revealed abnormal uptake in the lateral, inferior, and apical myocardium. These abnormalities resolved after coenzyme Q₁₀ therapy. This suggested that the ¹²³I-BMIPP test might be useful in detecting subclinical cardiac abnormalities associated with this mitochondrial mutation, and might be capable of being used to confirm the effects of Coenzyme Q₁₀ therapy. Furthermore, it can be inferred that vasomotor dysfunction may have induced her various autonomic symptoms. We conclude that in view of the circulatory dysfunction due to the mitochondrial abnormality caution is warranted when diagnosing mitochondrial diabetes mellitus patients with various autonomic symptoms.