12599 Early Remission Of Chromosome 6 Q 24-related Neonatal Diabetes Mellitus

Abstract Disclosure: R. Pratibha: None. K. Dummula: None. Introduction: Chromosome 6q24 imprinting abnormalities represent the predominant cause of transient neonatal diabetes mellitus (TNDM), accounting for over two-thirds of cases with an estimated prevalence of 1 in 400,000. While remission typically manifests by 3 months of age, herein we detail a case of Chromosome 6q24-related TNDM exhibiting remission by 1.5 months of age. We share our clinical experience in managing this case without hypoglycemia and using C-Peptide levels as a monitoring tool to track the resolution. Case: A female infant, born at 36 weeks via elective C-section due to fetal growth restriction and oligohydramnios, was closely monitored in the nursery for potential hypoglycemia. Contrary to the expectation, she displayed escalating hyperglycemia, necessitating insulin infusion within 25 hours of birth. Apgar scores were 7 and 9, and the birth weight was 2095 g (6th percentile). Maternal history included impaired glucose tolerance in a previous pregnancy with borderline glucose tolerance during this gestation. The newborn physical exam was unremarkable except for mild macroglossia. Despite initial blood glucose (BG) of 52 mg/dl, it rose to 257 mg/dL by 16 hours. Insulin drip was started at 24 hours due to BG of 304 mg/dL. The monogenic diabetes panel obtained on day of life (DOL) #2 was negative; no acidosis was observed. The C- Peptide was low at 0.2 ng/ml. Insulin infusion was continued until DOL # 20. A trial of glyburide commenced on DOL #9 while on Insulin drip, yielded minimal response, prompting a transition to short-acting insulin for correction of hyperglycemia (>250 mg/dL). C-peptide level during sulfonylurea (SU) trial remained low (0.5 ng/mL). The infant required 2 to 3 corrections per day with 0.05 units of Lispro Insulin, with the last dose administered at 44 days. She did not receive any long-acting Insulin. As of her last follow-up at the endocrine clinic at 57 days of age, the infant is thriving well and has normal blood glucose levels. The 6q24 Methylation-MLPA study showed duplication of 6q24 on the paternally inherited chromosome 6. Significantly, she never encountered hypoglycemia during her hospital stay. The C-peptide increased to 0.8 ng/ml at DOL#37 and had normalized to 1.3 ng/mL by DOL#57 indicating remission of TNDM. Conclusion: 6q24-related TNDM may often be characterized by features such as small for gestational age (SGA), macroglossia, umbilical hernia, cardiac and renal abnormalities. Early presentation of hyperglycemia with this phenotype must prompt its diagnostic evaluation. Early resolution by 1.5 months as seen in our case is uncommon. Uniquely, we used C-peptide as a tracking tool to guide resolution and manage insulin therapy. Presentation: 6/3/2024