Synergistic interaction between exercise and insulin on peripheral glucose uptake.

Abstract

A B S T R A C T The interaction of exercise and insulin on glucose metabolism was examined in 10 healthy volunteers. Four study protocols were used: study 1: plasma insulin was raised by -100 ,uU/ml while plasma glucose was maintained at basal levels for 2 h (insulin clamp). Study 2: subjects performed 30 min of bicycle exercise at 40% of VO2 max. Study 3: an insulin clamp was performed as per study 1. Following 60 min of sustained hyperinsulinemia, however, subjects exercised for 30 min as per study 2. Study 4: subjects were studied as per study 3 except that catheters were inserted into the femoral artery and vein to quantitate leg glucose uptake.During the 60-90-min period of hyperinsulinemia (study 1), glucose uptake averaged 8.73±0.10 mg/kg per min. With exercise alone (study 2), the increment in peripheral glucose uptake was 1.43±0.30 mg/kg per min. When hyperinsulinemia and exercise were combined (study 3), glucose uptake averaged 15.06±0.98 mg/kg per min (P < 0.01) and this was significantly (P < 0.001) greater than the sum of glucose uptake when exercise and the insulin clamp were performed separately. The magnitude of rise in glucose uptake correlated closely with the increase in leg blood flow (r = 0.935, P < 0.001), suggesting that the synergism is the result of increased blood flow and increased capillary surface area to exercising muscle. More than 85% of total body glucose metabolism during studies 1 and 3 was accounted for by skeletal muscle uptake.These results demonstrate that (a) insulin and exercise act synergistically to enhance glucose disposal in man, and (b) muscle is the primary tissue responsible for the increase in glucose metabolism following hyperinsulinemia and exercise.

Enhancement of whole body glucose uptake during and after human skeletal muscle low-frequency electrical stimulation

“…The novel and, moreover, clinically important finding of the present study is that whole body glucose uptake is acutely increased in response to 20 min of ES, and this increase lasts for at least 90 min after the cessation of ES under physiological hyperinsulinemia (ϳ70 U/ml). It is also notable that the postexercise increase in GDR is as high as that seen by bicycle exercise (40% of maximal oxygen uptake, 30 min) performed under similar hyperinsulinemia (ϳ77 U/ml) (5).…”

“…DeFronzo et al (5) have demonstrated that the stimulatory effect of exercise on glucose uptake under physiological hyperinsulinemia is correlated with increased blood flow to exercising muscles, and, in fact, Saltin et al (44) have found that ES at 50 Hz does increase leg blood flow in a work rate-dependent manner. It is likely that the increase in glucose uptake during and after ES could be due, at least in part, to a better perfusion of the peripheral tissue, which enhances glucose and insulin delivery in stimulated muscles.…”

Insulin resistance syndrome: possible key role of blood flow in resting muscle

“…Exercise has a well-known, beneficial effect on the metabolic control in Type 2 diabetes and is also a powerful stimulator of insulin-dependent glucose uptake in normal subjects. That blood flow is the limiting factor is indicated by a study combining insulin clamp with bicycle exercise and measurement of blood flow and glucose uptake in the leg [13]. A close correlation was found between glucose uptake and leg blood flow (r = 0.935).…”

Isoform-specific defects of insulin stimulation of Akt/protein kinase B (PKB) in skeletal muscle cells from type 2 diabetic patients

“…Type 2 diabetes is characterised by insulin resistance in peripheral tissues, particularly in skeletal muscle, which is responsible for more than 75% of whole-body glucose uptake in response to insulin [1]. The action of insulin is initiated through the binding of the hormone to its receptor, stimulating a cascade of phosphorylation events leading to activation of phosphoinositide 3-kinase (PI3K).…”