Emergence of insulin resistance following empirical glibenclamide therapy: a case report of neonatal diabetes with a recessive INS gene mutation.

BACKGROUND: As KATP channel mutations are the most common cause of neonatal diabetes mellitus (NDM) and patients with these mutations can be treated with oral sulfonylureas, empiric therapy is a common practice for NDM patients. CASE PRESENTATION: A non-syndromic, small for gestational age baby born to first-degree consanguineous parents was diagnosed with NDM. Because of hypo- and hyperglycemic episodes and variability in insulin requirement, we initiated a trial of glibenclamide, with a presumptive diagnosis of NDM caused by a KATP channel mutation. However, this empiric sulfonylurea trial did not improve the patient's glycemic control and resulted in resistance to exogenous insulin. Genetic testing identified a previously reported homozygous INS promoter mutation (c.-331C>G), which was not responsive to sulfonylurea therapy. CONCLUSIONS: In light of our results, we recommend to confirm the genetic diagnosis as soon as possible and decide on sulfonylurea treatment after a genetic diagnosis is confirmed.