ABCC8 Mutation Causing Permanent Neonatal Diabetes Mellitus in Early Infancy: A Case Report.

Introduction: Neonatal diabetes mellitus (NDM) is a rare monogenic form of diabetes presenting within the first 6 months of life. It can be transient or permanent; early diagnosis is essential to improve outcomes. Case Presentation: A 45-day-old male infant presented with fever, dehydration, and marked hyperglycemia. Initially misdiagnosed as meningitis, further evaluation revealed diabetic ketoacidosis, confirmed by elevated blood glucose and +4 urine ketones. He was stabilized with IV fluids and insulin, then transitioned to subcutaneous insulin. Persistent hyperglycemia and patient's age raised suspicion for NDM, warranting genetic testing, which identified a heterozygous pathogenic ABCC8 missense variant. Oral sulfonylurea was initiated using a locally compounded suspension due to limited resources. Insulin was successfully tapered, and euglycemia was achieved on sulfonylurea monotherapy. Discussion: Highlighted here is the importance of genetic testing in suspected NDM; it directly guides management. Shifting from insulin to oral agents improves glycemic control and long-term prognosis. Managing NDM in low-resource settings requires adaptive, multidisciplinary approaches. Ideally, patients should be followed into adolescence, focusing on neurodevelopment, as some variants may lead to neurological complications. Conclusion: Recognizing NDM in infants with unexplained hyperglycemia is important for timely, targeted treatment. Individualized care is possible in constrained settings, offering improved overall outcome.