There are two major types of diabetes mellitus: type 1 diabetes mellitus (T1D) which results from the self-destruction of insulin producing pancreatic beta cells and represents ~ 10% of all cases and the more prevalent type 2 diabetes mellitus (T2D) of complex and still elusive etiology featuring both impaired insulin secretion and resistance/decreased sensitivity in target tissues. The gene discussed is INS; the disease is type 2 diabetes mellitus.