Diabetes mellitus type 2 (formerly noninsulin-dependent diabetes mellitus (NIDDM) or adult-onset diabetes) is a metabolic disorder that is characterized by hyperglycemia (high blood sugar) in the context of insulin resistance and relative lack of insulin.besity is thought to be the primary cause of type 2 diabetes in people who are genetically predisposed to the disease (although this is not the case in people of East-Asian ancestry). Type 2 diabetes is initially managed by increasing exercise and dietary changes.