Exercise and Glycemic

Working muscle needs fuel. During aerobic activity such as brisk walking, cycling, or swimming, skeletal muscle increases its uptake of circulating glucose. This can lower blood glucose even when the person has not taken additional insulin. Insulin already circulating changes the risk. A person who exercised soon after a meal-time insulin dose may have both insulin and active muscle pulling glucose from the bloodstream. The result can be a rapid drop in glucose. Medications that stimulate pancreatic insulin release can create a similar risk because insulin secretion does not automatically decrease when exercise begins. Aerobic exercise usually lowers glucose during or shortly after the session. Resistance training and brief high-intensity activity may produce a temporary rise instead because catecholamines stimulate hepatic glucose release. That rise does not mean the patient is protected from a later low. The glucose-lowering effect of activity can last as long as 48 hours.