P-235: Neonatal diabetes mellitus due to KCNJ11 gene mutation: the decisive role of genetic testing in therapeutic response – a case report
M L d O Cerqueira, M M M Lucena, C A Coutinho, A C L NevesAbstract
Introduction
Neonatal diabetes mellitus (NDM) is an extremely rare form of diabetes with onset in the first six months of age, resulting from mutations in genes that affect pancreatic beta-cell function.
Objectives
To describe the clinical course of an infant with NDM and highlight the relevance of genetic testing in therapeutic decision-making.
Methods
A descriptive, retrospective case report based on medical record review, with authorization from the legal guardian.
Results
Male infant, 1 month and 15 days old, admitted with fever, hypoactivity, loss of appetite, watery diarrhea, and respiratory distress. Initially treated for neonatal sepsis, he presented with blood glucose of 534 mg/dL and generalized tonic-clonic seizures associated with hypocalcemia. He evolved with clinical and laboratory improvement but maintained persistent hyperglycemia (>200 mg/dL), leading to initiation of NPH insulin (0.3 IU/kg/day) and regular insulin. Over the first 5 years, during outpatient follow-up, tests showed negative autoantibodies, low C-peptide (0.17 ng/mL), and glycated hemoglobin (HbA1C) ranging from 6.2–7.5%, with multiple hospitalizations due to poor glycemic control. At 5 years and 8 months, using 1.1 IU/kg/day of insulin and presenting frequent dysglycemia, genetic testing was performed, confirming a KCNJ11 gene mutation (ATP-sensitive potassium channel – Kir6.2). He was hospitalized for transition from insulin to sulfonylurea, discharged on glibenclamide (0.5 mg/kg/day) and regular insulin. He showed good response, with no complications or new hospitalizations, improved glycemic control, and reduction in HbA1c (7.5% to 5%), with complete discontinuation of insulin after 6 years of sulfonylurea use.
Conclusions
This case highlights the importance of early diagnosis and genetic testing in NDM. Identification of the mutation enabled a therapeutic change with clinical and prognostic improvement, emphasizing the role of genetic diagnosis in individualized treatment.