Effect of strict metabolic control on regulation of subcutaneous blood flow in insulin-dependent diabetic patients.
The effect of 10 weeks of improved metabolic control on the impaired autoregulation of the subcutaneous blood flow was studied at the level of the lateral malleolus in eight long-term insulin-dependent diabetic patients with clinical microangiopathy. Blood flow was measured by the local 133-Xenon washout technique. Mean arterial blood pressure was reduced by a maximum of 23 mmHg by elevating the limb above heart level and elevated to a maximum of 65 mmHg by head-up tilt; in the latter position venous pressure was kept constantly low by activation of the leg muscle vein pump (heel raising). Improved metabolic control was achieved using either continuous subcutaneous insulin infusion or multiple insulin injections. The blood glucose concentration declined from (median) 12.7 to 6.8 mmol/l and the HbA1C level from 10.1 to 7.5% during strict metabolic control (p less than 0.01 and p less than 0.01, respectively). The slope of the subcutaneous blood flow autoregulation curves during poor metabolic control (median: 11.6% per 10 mmHg, range: 8.0-30.5% per 10 mmHg) was not significantly different from the slope values during improved metabolic control (13.4% per mmHg, 10.1-24.4% per mmHG). No association was demonstrated between the impaired autoregulation of subcutaneous blood flow and the metabolic parameters. Our results indicate that improved metabolic control for 10 weeks has no effect on the impaired autoregulation of subcutaneous blood flow in long-term insulin-dependent diabetic patients with clinical microangiopathy.