Monogenic diabetes arises due to mutation in a single-gene and is recognized by their striking familial inheritance pattern. This form of diabetes is inherited in an autosomal dominant or recessive fashion, unlike polygenic Type 1 (autoimmune) or type 2 diabetes caused by the combined action of more than one gene [1-11]. Monogenic diabetes is classified into three main groups: Neonatal diabetes mostly presents in the first six months of birth, maturity onset diabetes of the young (MODY) and maternally inherited mitochondrial diabetes. These mutations run in the family and have a predictable course. Most of the monogenic diabetes is treated with oral medications like sulfonylurea rather than insulin. ABCC8/KCNJ11 gene mutations also cause monogenic diabetes. This gene mutation has been found in ~50% of congenital hyperinsulinemia (CHI) patients. In such cases diabetes commonly presents in the neonatal period (transient or permanent) or at adolescence / early adulthood [1]. We present a 58-year-old diabetic lady, who was detected with ABCC8 mutation during the cascade testing [8]. She was diagnosed with diabetes at the age of 12 [8]. Her son had history of neonatal hypoglycaemia and developed diabetes at the age of 15. He was the index case who was found to have ABCC8 mutation. The family has several other members diagnosed with diabetes. The aim of the article is to increase awareness and understanding of monogenic diabetes among the medical practitioners in adult population with diabetes so that the genetic testing can be offered in a cost effective manner.