The Predominant Maturity-Onset Diabetes of the Young Subtype in Türkiye: Insights from a GCK-MODY Case and the Literature

Background: The genes mutated in monogenic diabetes vary across populations, and different clinical outcomes are observed depending on the affected gene. GCK-MODY, which develops as a result of a glucokinase gene mutation, is the most common subtype in Türkiye. This review aims to summarize the clinical presentations, mutations, and diagnostic and therapeutic approaches observed in MODY studies conducted in Türkiye.Review Text: Twelve studies conducted in Türkiye between 2015 and 2024 were analyzed for demographic, clinical, and molecular data. Additionally, one case compatible with GCK-MODY was evaluated. GCK-MODY was found to be the predominant MODY subtype in Türkiye, and GCK gene mutation rates ranged from 20% to 70% depending on study design and inclusion criteria. Patients with GCK-MODY were found to exhibit typical clinical features, including mild fasting hyperglycemia, HbA1c levels below 7%, negative autoantibodies, and preserved C-peptide levels. The presented 22-year-old female case demonstrated clinical and genetic features consistent with GCK-MODY.Conclusion: Data from studies in Türkiye indicate that GCK-MODY is the most common monogenic diabetes subtype, with the expected clinical features. Accurate clinical and molecular diagnosis is crucial for preventing unnecessary pharmacological treatment, providing appropriate treatment, and providing appropriate genetic counseling in special circumstances such as pregnancy.