INS and type 2 diabetes mellitus: T2DM develops when peripheral insulin resistance surpasses the ability of the pancreas to increase insulin production, resulting in overwhelming stress to insulin-producing β-cells and poor insulin responsiveness.24 After 16 weeks on Western diet, WT exhibited extreme hyperplasia of Langerhans islands, but had fasting hyperglycemia and impaired late response to glucose challenge, suggesting insufficient insulin secretion and T2DM.