INS and diabetes mellitus: In type 2 diabetes mellitus, insulin resistance and relative deficiency of insulin secretion are two characteristic features and current clinical therapies mainly focus on increasing plasma insulin level by direct insulin administration and oral agents that promote insulin secretion, improving insulin sensitivity by drugs such as thiazolidinediones (TZDs) and delaying the digestion and absorption of carbohydrate from the gastrointestinal tract by inhibition of α-glucosidase [2].