Prevalence and treatment of mitochondrial diabetes in Southwest Finland.

Purpose: Diabetes mellitus (DM) is a common manifestation of mitochondrial disease, typically associated with the mitochondrial DNA (mtDNA) variant m.3243A>G. We investigated the clinical features, treatment, and epidemiology of mitochondrial DM in the region of Southwest Finland. Methods: Electronic medical records at Turku University Hospital were searched for patients assigned ICD-10 codes E13.0-E13.9 during 2000-2022. Among 1004 screened individuals, nine patients with genetically confirmed mitochondrial diabetes were identified. Eight additional genetically confirmed patients were included from an ongoing mitochondrial disease research project, resulting in a cohort of 17 patients. The clinical characteristics and DM treatment of the patients were obtained from medical records. Results: We identified 17 patients with mitochondrial DM. Mean age at diagnosis of DM was 35 years (range 11 to 60 years). Most patients with mitochondrial DM had hearing impairment (14/17). Insulin treatment was typically initiated 3.5 years after the diagnosis of DM. Only six (35%) patients had HbA1c below 7.0% (53 mmol/mol). The prevalence of mitochondrial DM in the region of Southwest Finland in the end of 2022 was 2.7/100,000 and annual incidence during the study period 0.14/100,000. Conclusions: The onset of non-autoimmune diabetes in young adult age, particularly when associated with hearing impairment, suggests possible mitochondrial DM. Recognition of mitochondrial diabetes is essential for optimal management and complication prevention.