There are various causes of type 2 diabetes.Although the specific etiologiesare not known, autoimmune destructionof b-cells does not occur and patients donot have any of the other known causesof diabetes.Most but not all patientswithtype 2 diabetes are overweight or obese.Excess weight itself causes some degreeof insulin resistance. Patients who are notobese or overweight by traditionalweightcriteria may have an increased percentageof body fat distributed predominantlyin the abdominal region.