Patients with type 2 diabetes have impaired exercise-induced blood volume expansion, according to a new report.
Dr. Emile R. Mohler III from University of Pennsylvania School of Medicine, Philadelphia, stated that, "Diabetic vascular disease is complex, and this study indicates that it appears to affect artery function even before significant lower extremity arterial blockages occur."
Dr. Mohler and colleagues investigated the hemodynamic response to exercise of patients with and without diabetes and peripheral arterial disease (PAD) using near-infrared spectroscopy (NIRS).
Diabetic patients with a normal ankle-brachial index (that is, those without peripheral arterial disease) had significantly impaired skeletal muscle capillary blood volume expansion during exercise, the authors report.
Patients with peripheral arterial disease (but without diabetes) showed greater increases in exercise-induced blood volume than did healthy controls, the results indicate, but diabetic patients with peripheral arterial disease had attenuated blood volume responses compared with patients with peripheral arterial disease alone.
Diabetes alone had no effect on oxygen recovery times, the researchers note, but patients with peripheral arterial disease (with and without diabetes) had oxygen recovery times about 2.5 times longer than did healthy controls.
The relative deoxygenation and oxygenation recovery times correlated significantly with the presence of peripheral arterial disease and claudication, the report indicates, but not with the presence of diabetes.
"The impaired blood volume expansion likely reflects a decrease in the vasodilatation capacity of capillaries in the skeletal muscle of the lower extremity during physical activity," the authors conclude. "Patients with diabetes are known to have endothelial dysfunction, and it is likely that microvascular dysfunction contributes to the impaired blood volume expansion seen in this study."
Dr. Mohler noted that "PAD is typically more severe in diabetic patients than in comparable nondiabetic populations, and is associated with a worse prognosis. The American Diabetes Association recommends that all patients with diabetes undergo evaluation for PAD with measurement of the ankle-brachial index."
Diabetes Care 2006;29:1856-1859.