Neonatal diabetes mellitus is a monogenic disease that can present with hyperglycemia, dehydration, failure to thrive, and ketoacidosis within the first six months of life. Neonatal diabetes mellitus can be transient or permanent. Here, we describe a 10-week-old infant with transient neonatal diabetes mellitus who presented with diabetic ketoacidosis and was found to have heterozygous a de novo mutation, p.Thr1381Asn in the ABCC8 gene, which encodes the SUR1 protein. There was no family history of diabetes mellitus and the parents were negative for the mutation at ABCC8. The patient started on insulin therapy and remission of diabetes occurred at 4 months of age. The patient remained euglycemic over a 2-year follow-up period without necessitating any medicine.