 Research Design. General Approach. An open-label prospective clinical trial including 50 type 2 diabetic patients 25 diet-treated and 25 treated with diet plus sulfonylurea will have pioglitazone, 45 mg daily; added to their therapeutic regimen. All patients will be closely monitored and, in addition to periodic contacts and clinical visits, metabolic and vascular parameters will be assessed at the beginning and after 3 and 6 months of therapy. Euglycemic hyperinsulinemic clamp with muscle biopsies will be performed at the beginning and after 6 months of treatment. 