Personalized management of glucokinase-related monogenic diabetes (GCK-MODY) during pregnancy: a case report

Management of glucokinase-related monogenic diabetes (GCK-MODY) during pregnancy can be challenging.

We present the case report of a 33-year-old woman, diagnosed with diabetes since the age of 9. She had no micro or macrovascular complications, and HbA1c ranged between 6.5% and 6.8%, without pharmacological treatment. Family history revealed multiple relatives with the diagnosis of diabetes, including a maternal cousin with confirmed GCK-MODY. The patient underwent genetic testing that identified the variant NM_000162.5:c.829_830insCGG p.(Leu276_Val277insAla), heterozygous for the GCK gene, classified as of uncertain significance. During pregnancy, the couple chose not to undergo invasive fetal testing. Given the presumptive diagnosis of GCK-MODY and since fetal genotype was not determined, the pregnancy was managed under the assumption of a potentially unaffected fetus. During follow-up, combined with nutritional counseling and promotion of regular exercise, the patient required initiation of basal insulin therapy. Then, to optimize metabolic control, continuous glucose monitoring (CGM) was implemented, and insulin therapy was progressively intensified to a basal-bolus regimen, ultimately reaching eight daily bolus administrations of rapid-acting insulin. Adequate glycemic control and appropriate fetal growth were achieved, and she delivered a male newborn at 36 weeks and 2 days, with 2970g and APGAR score of 9 at 1, 5 and 10 minutes. Genetic testing of the mother and sister was requested during the patient's pregnancy, but the results became available only after delivery. These confirmed the presence of the same variant in both relatives, supporting the diagnosis of GCK-MODY.

This case highlights the complexity of managing presumptive GCK-MODY during pregnancy, in the setting of a variant of uncertain significance and absent fetal genotyping. It emphasizes the importance of CGM-guided intensive insulin therapy and the need for a multidisciplinary and individualized approach based on shared decision-making.