Regional variation in skin blood flow response to hypoglycaemia in type 1 (insulin-dependent) diabetic patients without complications

Body temperature falls during hypoglycaemia, perhaps as a protective mechanism. To test the hypothesis that the skin blood flow response to hypoglycaemia is specifically designed to facilitate heat loss we studied both nutritional blood flow and arteriovenous shunting of blood in skin during prolonged, controlled hypoglycaemia in man. We studied eight otherwise healthy, male, Type 1 (insulin-dependent) diabetic patients. Under Biostator control blood glucose was clamped at 8.0 (7.9-8.9), mmol/l (median and range) for 30 min, reduced to symptomatic hypoglycaemia, 1.7 (1.0-2.6) mmol/l for 20 min then raised to 4.9 (3.3-6.7) mmol/l. Interdigital skin web blood flow (laser doppler flowmeter, nutritional flow) fell during hypoglycaemia from 3.1 (2.2-3.8) to 2.4 (1.2-2.8) volts and remained depressed. In contrast, finger blood flow (venous occlusion plethysmography, arteriovenous shunt flow) started high at 54.7 (17.4-85.6), remained high at 52.7 (38.1-81.4) during hypoglycaemia but fell sharply to 25.3 (4.2-66.2) ml.min-1.100 ml-1 when symptoms were relieved. Plasma adrenaline and vasopressin both rose during hypoglycaemia from 0.4 (0.05-0.8) to 4.5 (2.3-20.2) nmol/l and from 0.5 (0.5-3.5) to 4.4 (2.0-13.9) pg/ml, respectively, and both fell sharply thereafter.