MON-131 A Case Report of Neonatal Diabetes Successfully Treated with Oral Glyburide before Genetic Testing

Background: A very rare disease, neonatal diabetes has historically been treated with subcutaneous insulin. A recent study showed efficacy of oral glyburide on a specific subset of newborns diagnosed with neonatal diabetes, and that it is safe to try even before genetic test results are available. Clinical Case: 1 day old male born at 41 weeks and 1 day was found to by hyperglycemic to the 300s. At that time, it was thought to be reactive hyperglycemia as he was in respiratory distress, had a pneumothorax, and his mother was GBS positive. He was started on an insulin drip, which was titrated to his blood glucose levels. At this time, serum insulin and C-peptide levels were found to be undetectable, confirming a diagnosis of neonatal diabetes (Insulin <1.0, n 2.0-19.6, C-peptide <0.10, n 0.8-3.85). Genetic testing was sent on genes commonly responsible for neonatal diabetes. On day of life 12 (DOL 12), he was started on diluted subcutaneous insulin Lispro. He was exquisitely sensitive to small amounts of insulin and was often hypoglycemic after even 0.1 units of diluted insulin (0.01u of commercial insulin Lispro). On DOL 14, as genetic testing results were still pending, he was started on oral glyburide. The drug was administered twice daily, but he remained hyperglycemic requiring advancement of the target dose to 0.5mg/kg/day. On DOL 22, Insulin and C-peptide levels were drawn after subcutaneous insulin had been discontinued for 48 hours. While not yet within normal limits, both values increased to detectable levels, demonstrating objective response the the glyburide therapy (Insulin 1.1, n 2.0-19.6, C-peptide 0.32, n 0.8-3.85). Ultimately, this dose of glyburide was too high for him, and he was discharged home on DOL 26 with 0.036mg/kg/day that will be titrated up as an outpatient as he continues to grow. Since discharge, his blood glucose levels have ranged between 100-200, with no values below 85. Interestingly, his first genetic testing results came back negative for all the mutations in the panel, including the most common mutations in neonatal diabetes that respond to sulfonylurea therapy, ABCC8 and KCNJ11. He is in the process of being enrolled in the a Neonatal Diabetes Registry where they will test for other genes implicated in neonatal diabetes. Conclusion: This is a case of neonatal diabetes with an unknown gene mutation showing efficacy of oral glyburide therapy.