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.