Type 2 diabetes is a lifestyle disease, often with a genetic component. Being overweight, unfit, and eating poorly are risk factors. Certain ethnic communities are more susceptible to type 2 diabetes, as are some families.
Physical activity and formal exercise, along with a healthy diet and watching your weight, can help to prevent type 2 diabetes, and help those who have the condition to manage it. Expert organizations such as the American Diabetes Association have confirmed this, and both weight and strength training can be important parts of an exercise program in this prevention strategy.
Type 2 diabetes is a disease characterized by abnormally high blood glucose that results from insufficient insulin (the glucose-storage hormone), or insulin's not working well enough. Diabetes can cause further problems if not treated, progressing to heart and artery disease, as well as nerve damage.
Type 2 diabetes usually occurs in adults. Type 1 diabetes, previously called juvenile diabetes, usually shows up in young children and is not initially related to lifestyle. Even so, aspects of physical conditioning can assist all diabetics in some way.
Fitness and Function
Physical fitness, of which weight training should be a part, improves heart and lung fitness, and normalizes the metabolism along with the other known benefits for strength, muscle, flexibility and physical function.
While strength enhancement improves quality of life in sedentary people, muscle development not only improves strength, but crucially extra muscle means increased storage for glucose in the form of glycogen. Glucose, which is problematically high in the bloodstream in type 2 diabetics, is stored in muscle and the liver. Enhancing the efficiency of this process can help diabetics.
(Interestingly, aerobic fitness will increase liver storage of glucose as well.)
Glucose and Insulin
As well as increasing storage depots for glucose, weight training (and fitness in general) improves the function of insulin. In diabetics, insulin function degrades and cannot get glucose across to storage in muscle and liver efficiently. Eventually, insulin production can decline, requiring a person to inject insulin to replace that function.
Resistance training has been shown to improve the efficiency of insulin function.
A regular exercise workout is an essential part of most weight loss programs. For diabetics, weight training exercise not only helps improve glucose and insulin function, but assists with weight loss, which also helps improve glucose and insulin function. It's no wonder that combining exercise and weight loss (and healthy eating) is such a potent tool in arresting the progression of diabetes.
Heart and Blood Pressure
Exercise and physical activity are potent regulators of all-around heart and lung fitness, including blood pressure. The higher the level of fitness, as measured by easily-measured parameters such as blood pressure and resting heart rate, the less likely diabetes is to occur or progress, except in circumstances where genetic or other factors are involved.
In earlier years, it was thought that resistance exercise might raise blood pressure — as it does intermittently during exercise execution — but the overall effect is to lower blood pressure as physical fitness improves.
Note: Diabetics should only undertake exercise programs with the approval of their doctor. In addition, type 1 diabetics and insulin-using type 2 diabetics may need to adjust their insulin dose with some exercise programs.
Types of Exercise
In a consensus statement, the American Diabetes Association has recommended:
- For people with impaired glucose tolerance (IGT), 150 minutes of moderate to vigorous physical activity each week, including aerobic exercise and weight training.
- Performing 4 hours/week of moderate-to-vigorous aerobic and/or resistance exercise physical activity is associated with greater CVD (cardiovascular disease) risk reduction compared with lower volumes of activity.
- In the absence of contraindications, people with type 2 diabetes should be encouraged to perform resistance exercise three times a week, targeting all major muscle groups, progressing to three sets of 8–10 repetitions at a weight that cannot be lifted more than 8–10 times (8–10 RM).
Sigal RJ, Kenny GP, Wasserman DH, Castaneda-Sceppa C, White RD. Physical activity/exercise and type 2 diabetes: a consensus statement from the American Diabetes Association. Diabetes Care. 2006 Jun;29(6):1433-8.