Lowering Physical Activity Impairs Glycemic Control, Even in Healthy People

Low levels of physical activity — like the 5,000 steps per day that Americans typically achieve, which is only about half of the recommended amount — have been implicated in the development of insulin resistance and its progression to full blown type 2 diabetes. However, the studies that suggested this connection were performed under laboratory conditions; they did not use people eating real meals, and they did not assess glycemic variability, so the direct impact of physical activity on glycemic control is not completely clear.

People walking down the street

Elevated postprandial glucose (PPG) often precedes the development of type 2 diabetes, and is a risk factor for adverse cardiovascular events, independently of diabetes status. Thus, Dr. Catherine Mikus and her colleagues at the University of Missouri set out to precisely define the impact of reducing physical activity on PPG and glycemic variability in healthy, active volunteers as they went about their daily lives. The results of their study were recently published in the journal Medicine and Science in Sports and Exercise [1].

The Glycemic Index

The Glycemic Index (GI) is a system for rating carbohydrates, or saccharides, based on their immediate effect on the blood glucose level. An organic compound, glucose is a simple sugar or monosaccharide. Glucose is the principle sugar circulating in the blood; all cells use glucose as a source of energy and as a metabolic intermediate. Found in plants, glucose is the product of photosynthesis (the process of converting light energy to chemical energy and storing it in the bonds of a glucose molecule). Biologically active glucose is often referred to as dextrose. Glucose is often incorrectly referred to as table sugar – table sugar is a disaccharide composed of glucose and fructose.