The Effect of Repetitive Exercise on Daily Control of Glycemia in Insulin-Dependent Diabetic Patients

Abstract

In the postabsorptive state, glucose needs of the muscle are met by a precisely matched release of glucose from the liver (1). The precise nature of this coordination is not yet known, but many regulatory components have been investigated systematically. Glucose production increases under the influence of decreased levels of insulin and increased levels of glucagon (2) and catecholamines (3). A number of endogenous factors can affect glucose utilization: muscular activity factors (4), nonsuppressible insulin-like activity (5), changed sensitivity of insulin receptors (6), hypoxia (7) and changes in cytoplasmatic calcium levels (8). The relative importance of these factors is not established, but they may act as amplifiers of insulin, which(on the basis of in vivo and in vitro data) is considered to be essential for stimulation of glucose uptake during exercise (1,9). It is also indicated that increased blood flow and augmented capillary area can provide an adequate amount of insulin to the muscle, even when its concentration in blood is low (1). Catecholamines can interfere with glucose uptake by the muscle directly by increasing muscle glycogenolysis and indirectly by increasing lipolysis and then enhancing oxidation of fatty acids in the working muscle (for review see reference 10)