Early-Remitting Neonatal Diabetes in a Growth-Restricted Preterm Infant Requiring Insulin: A Case Report

Neonatal diabetes mellitus is a rare cause of persistent hyperglycemia in early infancy and is usually monogenic. We describe a male preterm neonate born at 34 weeks’ gestation with intrauterine growth restriction who developed severe hyperglycemia from the first days of life. Plasma glucose reached a maximum of 570 mg/dL with persistent glycosuria, negative urine ketones, and a normal acid-base profile. C-peptide was profoundly suppressed (0.01 ng/mL), supporting marked endogenous insulin deficiency. Following optimization of glucose administration, intravenous short-acting regular human insulin was initiated with hourly glucose monitoring and complicated by early asymptomatic hypoglycemia requiring rapid correction and insulin dose reduction. As enteral feeds started, treatment was switched to micro-dosed subcutaneous short-acting regular human insulin with the use of a freshly prepared dilution and a pre-feed threshold strategy. Insulin requirements progressively decreased, and therapy was discontinued by three months of age with maintenance of normoglycemia and normal glycated hemoglobin (HbA1c). Growth and neurodevelopment were normal through two years of follow-up. This case highlights the importance of keeping neonatal diabetes in mind for preterm, growth-restricted infants with persistent severe hyperglycemia requiring insulin after exclusion of secondary causes, and also to master the details of practical safety considerations for insulin use in early life.