Arterial, arterialized venous, venous and capillary blood glucose measurements in normal man during hyperinsulinaemic euglycaemia and hypoglycaemia

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Abstract
The purpose of this study was to evaluate the effectiveness of the warm-air box method on the arterialization of venous blood during euglycaemia and hypoglycaemia. Six healthy male volunteers were studied using an i.v. infusion of insulin (144 mU·kg−1·h−1). Arterial blood glucose was clamped at the baseline level for the first 30 min and subsequently reduced to 3.2 and to 2.5 mmol/l for 20 min. At each stage, including prior to insulin infusion, arterial, arterialized venous (heating the hand in a warm-air box set to 55–60°C), venous and capillary blood samples were taken simultaneously for analyses of blood glucose and oxygen saturation (not for capillary blood). The oxygen saturations in arterialized blood were approximately 3% below the arterial values. The arterial-arterialized difference of blood glucose was about 0.1 mmol/l (the 95% confidence interval: from −0.19 to 0.41 mmol/l), which tended to correlate with the difference in oxygen saturations between the arterial and arterialized blood samples (r=0.25, p=0.08). During the test the forearm venous blood oxygen saturation increased by 9% and the arteriovenous difference in blood glucose ranged from 0.2 to 0.5 mmol/l which correlated significantly with the difference in oxygen saturations (r=0.48, p<0.001). Capillary glucose was similar to the arterialized value. Rectal temperature was stable during the experiment. We conclude that the heated hand technique using the warm-air box sufficiently arterializes venous blood so that the glucose measurement in the arterialized blood provides a reasonable estimate of the arterial value and that the venous blood from the contralateral forearm is also markedly arterialized, probably reflecting a vasodilator effect of heating.