Coexistence of Maturity-Onset Diabetes of the Young Type 3 (MODY 3) and Diabetic Ketoacidosis: A Report of a Rare Case

Maturity-onset diabetes of the young (MODY) is a monogenic form of diabetes often misclassified as type 1 or type 2 diabetes. We report a young woman initially diagnosed with type 1 diabetes following gestational hyperglycaemia. Autoimmune testing was negative, and genetic analysis confirmed an <i>HNF1A</i> mutation consistent with maturity-onset diabetes of the young type 3 (MODY 3). Despite sulfonylurea therapy, she required insulin and experienced recurrent diabetic ketoacidosis (DKA) due to poor adherence. Improved engagement and continuous glucose monitoring led to marked glycaemic improvement. This case highlights the diagnostic challenge of MODY presenting with DKA, a rare occurrence in this condition. Early genetic testing is essential for accurate diagnosis, personalised management, and family counselling.