An infant with diabetes mellitus: Is it always T1DM? Soham Mukherjee a , Ashu Rastogi a , Radha Venkatesan b , Gopi Sundaramoorthi b , Viswanathan Mohan b , Anil Bhansali a, * a Dept. of Endocrinology, PGIMER, Chandigarh, India b Dept. of Molecular Genetics, Madras Diabetes Research Foundation, India ARTICLE INFO Article history: Received 28 January 2016 Accepted 23 July 2016 Available online 28 July 2016 Keyword: Neonatal diabetes novel ABCC 8 gene mutation ABSTRACT Here we describe a 2 1/2 month old infant with neonatal diabetes mellitus (NDM) who was initially misdiagnosed to have T1DM and initiated on insulin. He was found to have a novel heterozygous mutation Arg992Cys in ABCC 8 gene and successfully switched to oral anti- diabetic drug. Ó 2016 Elsevier Ireland Ltd. All rights reserved. 1. Introduction Neonatal diabetes mellitus (NDM) is a monogenic disorder which usually presents within the first 6 months of life and usually misdiagnosed as T1DM [1]. It is a genetically heteroge- neous group of disorders, which may results from develop- mental defect of pancreas and islets or b-cell dysfunction (K ATP channel dysfunction) [2]. NDM can be transient or per- manent [2]. We here report a case of permanent neonatal dia- betes with novel mutation in ABCC8 gene. 2. Case report A2 1/2 month old male infant, born to non-consanguineous parents presented with polyuria and polyphagia for the last 1 month. At presentation his RBG was 460 mg/dl, serum b (OH) butyrate 0.1 mmol/L, arterial blood gas showing no evi- dence of acidosis (pH-7.36) and HbA1C 10.7%. Anti GAD-65 antibody was negative. Ultrasonography ruled out structural disease of pancreas. There was no history of similar illness in the family. Patient was born-off normal vaginal delivery and had birth weight of 2.5 kg. The antenatal period was unremarkable with normal motor and developmental milestones. On examination he was conscious and had no dysmorphic feature. His weight was 4.3 kg, length 62 cm and head circumference 38 cm. He was initiated on insulin infu- sion, but his insulin requirement was very high (4.9 unit/kg/ day). As T1DM is uncommon before 6 months of age, there- fore the possibility of NDM was considered and glibenclamide was added. Insulin requirement markedly reduced to 1.4 units/kg/day on the first day and later insulin was discon- tinued. Patient was discharged with glibenclamide 2.5 mg per day with blood glucose values between 100 and 200 mg/dl. During follow-up at 3 months he had FPG 118 mg/dl, fasting plasma Insulin 12.46 lIu/ml, fasting C peptide 2.22 ng/ml and HbA1C was 5.7%. Genetic analysis revealed a novel heterozygous mutation Arg992Cys in ABCC8 gene in both patient and his mother. Father did not carry the same mutation. Chromatogram of this mutation is depicted in Fig. 1. Gradually his requirement for glibenclamide reduced to 0.6125 mg/day and at 1 year of follow-up his HbA1c was 5.2% and glibenclamide was stopped. At 2 years of follow-up his HbA1c was 6% which suggests persistent dysglycemia. http://dx.doi.org/10.1016/j.diabres.2016.07.014 0168-8227/Ó 2016 Elsevier Ireland Ltd. All rights reserved. * Corresponding author. E-mail address: anilbhansaliendocrine@gmail.com (A. Bhansali). diabetes research and clinical practice 125 (2017) 62 – 64 Contents available at ScienceDirect Diabetes Research and Clinical Practice journal homepage: www.elsevier.com/locate/diabres