Impaired autoregulation of blood flow in skeletal muscle and subcutaneous tissue in long-term Type 1 (insulin-dependent) diabetic patients with microangiopathy

Autoregulation of blood flow was studied in skeletal muscle and subcutaneous tissue in seven Type 1 (insulin-dependent) diabetic patients (median age: 36 years) with nephropathy and retinopathy and in eight normal subjects of the same age. Blood flow was measured by the local 133Xe washout technique. Reduction in arterial perfusion pressure was produced by elevating the limb 20 and 40 cm above heart level. Blood flow remained within 10% of control values when the limb was elevated in normal subjects. In five of the seven diabetic subjects blood flow fell significantly in both tissues when the limb was elevated 40 cm indicating impaired autoregulation. The results suggest that intrinsic vascular (arteriolar) mechanisms (myogenic and/or metabolic) underlying the normal autoregulatory response are defective in some diabetic patients with microangiopathy.