A Case Report of Mitochondrial Diabetes Mellitus Caused by Gross Deletion of Mitochondrial Gene and Literature Review

Mitochondrial diabetes mellitus is a rare disease caused by mutations in mitochondrial genes or nuclear DNA encoding components of the mitochondrial respiratory chain， and the clinical phenotype is diverse depending on the involved organs. We report a girl manifested with growth failure and diabetes mellitus. After systematic evaluation, bilateral sensorineural hearing loss, bilateral basal ganglia calcification, and abnormal electroencephalogram were found. The lactate exercise test showed that lactate was obviously increased immediately after exercise, suggesting dysfunction of mitochondria. A gross deletion of mitochondrial gene m.8649-m.16084 was discovered by mitochondrial gene sequencing. We make a literature review of the pathogenesis, genetic characteristics, and treatment of mitochondrial diabetes mellitus, as well as mitochondrial diseases harboring large fragment deletions manifested with diabetic phenotypes, to provide reference for clinical diagnosis and treatment of such diseases.