Diabetes Mellitus was Definitively Diagnosed after the Birth of the Second Child in A Case With an ABCC8 Pathogenic Variant

Abstract

The patient was a 29-year-old female. Her first child had had postnatal hyperglycemia, and at 1 month old, genetic testing had revealed a polymorphism in the ABCC8 gene in both the mother and child. A 75-g oral glucose tolerance test (OGTT) performed at 17 weeks' gestation for the second child was positive at 3 points, so the patient was diagnosed with gestational diabetes mellitus. Insulin therapy was initiated at 21 weeks' gestation. Postpartum insulin therapy was discontinued; however, the plasma glucose levels were 159 mg/dL at 0 min, 315 mg/dL at 60 min, and 338 mg/dL at 120 min. The HbA1c level was 6.6 % during the 75-g OGTT at 2 months postpartum, leading to a diagnosis of diabetes, and insulin therapy was started. Considering that diabetes mellitus was caused by the ABCC8 gene variant and that glycemic control was poor despite insulin therapy, glycemic control rapidly improved when glibenclamide 1.25 mg/day was initiated. Diabetes due to ABCC8 genetic disease has a varied age of onset and onset patterns; however, sulfonylureas have been reported to be effective, and an accurate diagnosis is important.