Case 6-2020: A 34-Year-Old Woman with Hyperglycemia

A 34 year old woman presented with a history of persistent hyperglycemia since age 24, initially misdiagnosed as type 2 diabetes. Despite lifestyle modifications and metformin, her glycemic control remained stable but elevated. During four pregnancies, she required insulin for gestational diabetes, with variable fetal outcomes. Genetic testing revealed a likely pathogenic variant in the GCK gene (p.Ser263Pro), confirming maturity onset diabetes of the young (GCK-MODY). This autosomal dominant form of diabetes causes mild, nonprogressive hyperglycemia due to impaired glucokinase function in pancreatic beta cells. Unlike type 2 diabetes, GCK-MODY typically does not require treatment outside pregnancy and carries low risk for complications. The case highlights the importance of genetic testing in young-onset diabetes with atypical features, as accurate diagnosis alters management discontinuing unnecessary medications and guiding pregnancy care based on fetal genotype. Family screening identified the same variant in her father and daughter, demonstrating its inheritance pattern.

A 34 year old woman presented with a history of persistent hyperglycemia since age 24, initially misdiagnosed as type 2 diabetes. Despite lifestyle modifications and metformin, her glycemic control remained stable but elevated. During four pregnancies, she required insulin for gestational diabetes, with variable fetal outcomes. Genetic testing revealed a likely pathogenic variant in the GCK gene (p.Ser263Pro), confirming maturity onset diabetes of the young (GCK-MODY). This autosomal dominant form of diabetes causes mild, nonprogressive hyperglycemia due to impaired glucokinase function in pancreatic beta cells. Unlike type 2 diabetes, GCK-MODY typically does not require treatment outside pregnancy and carries low risk for complications. The case highlights the importance of genetic testing in young-onset diabetes with atypical features, as accurate diagnosis alters management discontinuing unnecessary medications and guiding pregnancy care based on fetal genotype. Family screening identified the same variant in her father and daughter, demonstrating its inheritance pattern.