The glitazones, also known as insulin sensitizers, represent a new concept in the treatment of type 2 diabetes. While previously available antidiabetics have no influence on an existing insulin resistance, the glitazones act directly on the receptors in the muscles, fatty tissue and liver, and in this way reduce insulin resistance. To date, three members of this group of substances are known: troglitazone, rosiglitazone and pioglitazone. In a study done to investigate pioglitazone, fasting blood sugar and HbA1c achieved virtually normal values, and lipid metabolism also improved. On the basis of the results of studies done to date, the tolerability of both pioglitazone and rosiglitazone is good. In contrast to troglitazone, no evidence has been found for a hepatotoxic effect. Insulin sensitizers do not cause hypoglycemia, since they do not stimulate the pancreas. They are suitable both for monotherapy and combination treatment with metformin, sulfonylureas and insulin.