Type 1 diabetes mellitus (T1DM) results from inadequate insulin production by the endocrine pancreas.1 Type 1 diabetes mellitus can be classified based on its etiopathogenesis into immune-mediated T1DM (type 1A or T1DMA) and idiopathic T1DM (type 1B or T1DMB). The gene discussed is INS; the disease is diabetes mellitus.