There are three kinds of effective drugs for treating type 2 diabetes mellitus: (1) biguanide, which increases the sensitivity to insulin; (2) sulfonylurea, which promotes the secretion of serum insulin, and (3) α-glucosidase inhibitors, such as acarbose and voglibose, which reduce the sugar concentration in the blood. The gene discussed is INS; the disease is type 2 diabetes mellitus.