Insulin action enhancement normalizes brachial artery vasoactivity in patients with peripheral vascular disease and occult diabetes

Purpose: Brachial artery vasoactivity (BAVA) evaluation is a reliable, noni nvasive method of assessing arterial endothelial function in vivo. We previ ously have shown that patients with peripheral vascular disease (PVD) and o ccult diabetes have abnormal BAVA results when fasting and after oral gluco se intake during oral glucose tolerance test (OGTT). Troglitazone is an ora l hypoglycemic agent that enhances the action of insulin. The effect of tro glitazone on BAVA in patients with occult diabetes and PVD is not known. Methods: Patients with PVD, normal fasting glucose levels, and abnormal OGT T results were identified. With a duplex ultrasound scan, BAVA was evaluate d by measuring the brachial artery (BA) flow (in millimeters per minute) be fore and after 5 minutes of BA occlusion during fasting and at 30 minutes, 1 hour, and 2 hours after the administration of 75 g of glucose during OGTT . Troglitazone therapy (400 mg/day) was begun, and the BAVA evaluation was repeated after 2 and 4 months. These results were compared with the results of the control group who had normal fasting glucose levels, normal OGTT re sults, and no evidence of PVD. A paired t test was used to compare the BA f low before and after BA occlusion, with a P value of less than .05 consider ed significant. Results: The control group had a normal hyperemic response with a significa ntly increased BA flow after 5 minutes of BA occlusion during fasting and a t all stages of the OGTT. The occult diabetic group had an abnormal respons e to hyperemia before the treatment with troglitazone and showed little cha nge in flow after BA occlusion. After 2 months of troglitazone therapy, BAV A results improved after oral glucose intake but not during fasting. After 4 months, BAVA results normalized both while fasting and after oral glucose intake during the OGTT. Conclusion: Patients with occult diabetes and PVD have impaired BAVA, which normalizes after treatment with troglitazone, Insulin-action enhancers may slow the progression of PVD in patients with diabetes by improving endothe lial cell function. Agents that are aimed at enhancing the action of insuli n may have an advantage over the other traditional therapies for diabetes.