Sulfonylurea treatment in an infant with transient neonatal diabetes mellitus caused by an adenosine triphosphate binding cassette subfamily C member 8 gene mutation.

Neonatal diabetes mellitus (NDM) is an insulin-requiring monogenic form of diabetes that generally presents before six months of age. The following two types of NDM are known: transient NDM (TNDM) and permanent NDM (PNDM). Here we report on an infant with TNDM caused by a mutation (p.Gly832Cys) of the gene for the ATP binding cassette subfamily C member 8 (ABCC8). The patient exhibited hyperglycemia (600 mg/dL) at five weeks of age and insulin treatment was initiated. As genetic analysis identified a missense mutation within ABCC8, the insulin was replaced by glibenclamide at five months of age. Thereafter, the insulin was successfully withdrawn and his glycemic condition was well controlled at a dose of 0.0375 mg/kg/d. Since the patient's blood glucose was under control and serum C-peptide levels were measurable, glibenclamide was stopped at 1 yr, 10 mo of age. The lack of DM relapsed to date confirms the TNDM diagnosis. In conclusion, when insulin is replaced with a sulfonylurea-class medication (SU) in NDM patients, serum C-peptide levels should be closely monitored and fine adjustment of SU dose is recommended.