Exercise and Insulin Sensitivity
Lifestyle programs such as physical activity and weight loss enhance insulin sensitivity in obese individuals and people with diabetes. These programs also prevent or delay the onset of diabetes with individuals at risk for diabetes. Weight loss alone is able to improve insulin resistance by a decrease in intramuscular fat deposit. On the other hand, exercise by itself has been shown to improve insulin resistance in the absence of weight loss by enhancing mitochondrial function. Mitochondria are organelles in every cell and often described as the “powerhouse”. They are the sites where glucose and fat are burnt or oxidized to produce chemical energy called ATP to sustain life. Excessive fat deposit inside the cell is associated with mitochondrial dysfunction and insulin resistance. Interestingly, an exercise session can acutely sensitize mitochondria and cause a profound improvement in insulin sensitivity that can last for hours and even days
Diabetic Patients and Exercise Training
A 2010 study examined whether exercise training could reverse mitochondrial dysfunction and improve insulin resistance in patients with type 2 diabetes. In a 12-week study, 18 male type 2 diabetic and 20 healthy male control subjects with family history of diabetes participated in a combined progressive training program. The exercise regimen consisted of 3 times per week with each session lasting 45 mins. Both groups had comparable body weight, age, BMI and maximal oxygen uptake. The diabetic subjects were on oral antidiabetic agents and both groups led a sedentary lifestyle and were not dieting. The results for the diabetic group showed that exercise training restored mitochondrial function with improvement in both glucose disposal and metabolic flexibility.