Diabetes mellitus (DM) is a group of chronic metabolic disorders characterized by elevated glucose in blood (hyperglycemia) and urine (glycosuria) resulting either from partial or absolute insulin deficiency due to autoimmune destruction of β cells (type 1 DM, T1DM) or from a significant reduction in the ability of cells to respond to insulin (insulin resistance) accompanied by a progressive loss of insulin secretion by β cells (type 2 DM, T2DM). The gene discussed is INS; the disease is type 1 diabetes mellitus.