KCNJ11 gene activating mutations play a major role in the development of neonatal diabetes mellitus (NDM). KCNJ 11 gene encodes the Kir 6.2 subunit of ATP- sensitive potassium channel which is a critical regulator of pancreatic beta-cell insulin secretion. To study KCNJ11 gene mutations in infants with NDM and the effect of sulfonylurea treatment on the glycemic control in patients with KCNJ11 gene mutation. Thirty infants with NDM were screened for KCNJ11 gene mutations by DNA sequencing, insulin therapy was replaced by sulfonylurea treatment in patients with mutations. R201C heterozygous mutation was found in one patient who was successfully shifted from insulin therapy to sulfonylurea treatment, while E23k, I337V, and S385C polymorphisms were detected in 14 patients. Screening for KCNJ 11 gene mutations could lead to identification of patients with mutations who can be successfully shifted from insulin therapy to sulfonylurea treatment improving their quality of life.