Studies on peripheral glucose metabolism using the experimental human forearm preparation.

Abstract

Metabolic studies on the human forearm glucose uptake are described. The results of these investigations can be summarized as follows: the mean fasting forearm glucose uptake of normal subjects was found to be + 0.53/gmmol/min/100 ml of forearm (S.E. ± 0.20), of fasting insulin-dependent diabetics −0.32 μmol/min/100 ml of forearm (S.E. ± 0.59) and of fasting insulin-independent diabetics of −0.50 μmol/min/100 ml of forearm (S.E. ± 0.23). — Statistical analysis of these data show that in 3 insulin-dependent diabetic patients there is a significant correlation between arterial blood glucose and forearm glucose uptake pointing to a peripheral tissue threshold above which the glucose molecule moves from the intravascular space to the intracellular compartment. — No significant correlations were found between the deep venous blood glucose of the forearm and the forearm glucose uptake in the same patients. — The injection of 0.1 units glucagon-free insulin into the brachial artery increases the forearm glucose uptake without affecting the arterial blood glucose. Greater doses decrease the arterial blood glucose inhibiting the hepatic glucose output. — On the other hand in the insulin-dependent diabetics no peripheral insulin effect was shown with the same or higher insulin doses indicating that these patients may have a peripheral tissue resistance to the insulin action. — The mean average forearm phosphate uptake was estimated to be + 0.03 μmol/min/100 ml of forearm (S.E. ± 0.04) in normals and. − 0.03,μmol/min/100 ml of forearm (S.E. ± 0.13) in diabetics. Furthermore the statistical analysis of these data showed that there is a significant relationship (P < 0.05) between the forearm glucose uptake and the forearm phosphate uptake both in normals and in diabetics. This should mean that the phosphate molecule follows the glucose molecule moving from the extracellular space to the intracellular space according to the insulin effect. — Finally the mean fasting forearm potassium uptake was −0.93 /gmmol/min/100 ml of forearm (S.E. ± 0.45) in normals and −0.90 μmol/min/100 ml of forearm (S.E. ± 2.7) in diabetics. No significant correlations were found between the forearm glucose uptake and the potassium glucose uptake in either normals or diabetic patients.