Mitochondrial Dysfunctions Driving Insulin Resistance

The overarching aim of this observational study is to characterize muscle mitochondrial defects in individuals harboring pathogenic mitochondrial DNA (mtDNA) mutations associated with an insulin-resistant phenotype. In a case-control design, individuals with pathogenic mtDNA mutations will be compared to controls matched for sex, age, and physical activity level. Participants will attend a screening visit and two experimental trials including: * An oral glucose tolerance test * A hyperinsulinemic-euglycemic clamp combined with measurements of femoral artery blood flow and arteriovenous difference of glucose * Muscle biopsy samples