According to the American Diabetes Association, Diabetes is one of the largest threats to the health of the United States population, with 24% of males and 33% of females born after the year 2000 having a chance of developing diabetes in their lifetime. Of the estimated 16 million Americans with diabetes, only 8 million have been diagnosed. Diabetes is the 7th leading cause of death from direct means, but this statistic greatly underestimates the role diabetes plays in premature death and disability.
Diabetes is classified into groups based on the cause of the disease.
• Insulin Dependent Diabetes Mellitus (or Type I as it is commonly known).
Insulin dependent diabetes is thought to be caused by a genetic autoimmune disorder that occurs in children. The beta cells in the pancreas responsible for the production of insulin are destroyed by the immune system, leading to a deficiency of circulating insulin. This is precisely what happen to me in 1971 when my father came home from work one day and found me on the bathroom floor unconscious after I had spent several days drinking what seemed like gallons of cool-aid due to dehydration, followed by frequent urination and vomiting. This cycle continued for days with my parents thinking I had the flu or some other illness brought home from elementary school. The symptoms as we later found out were the result of high levels of ketones, which can poison the body or even cause death when levels get too high. When your cells don’t get the glucose they need for energy, your body begins to burn fat for energy, which produces ketones. Ketones are acids that build up in the blood and appear in the urine when your body doesn’t have enough insulin. The result of my body burning fat for energy because of my pancreas no longer producing insulin, led to the development of diabetic ketoacidosis and later the diagnosis of type I diabetes.
• Non-Insulin Dependent Diabetes Mellitus (or Type II diabetes).
Non-insulin dependent diabetes results from insulin insensitivity of muscle cells, a reduction of insulin due to impaired secretion or a combination of both. This form is the most common of diabetes, representing more than 90% of all diagnosed cases; however it is also the most preventable.
Even though strong genetic factors exist, and the disease is more common in older age, the primary causes of non-insulin dependent diabetes (Type II) are all modifiable. Physical inactivity, obesity, and poor diet lead to the development of insulin resistance, glucose intolerance, and hyperinsulinemia (excessive secretion of insulin). When circulating glucose is not managed and remains elevated, it damages large and small vessels of the vascular system. Diabetic damage to blood vessels causes chronic complications and accounts for the significant morbidity (decreased quality of life and disability) and mortality related to the disease. These include:
• Large Vessel (macrovascular) Disorders – coronary heart disease, stroke, and peripheral vascular disease, which are the main causes of death.
• Small Vessel (microvascular) Disorders – retinopathy, nephropathy, erectile dysfunction, and neuropathy, which are the main causes of morbidity.
Inactive lifestyles are linked with the development of non-insulin dependent diabetes. Physical activity has shown to both protect against and have a pronounced effect on non-insulin dependent diabetes by reducing circulating glucose in a process that causes insulin re-sensitivity in the cells. The results of a National Population Health Survey showed that physically inactive women ages 55-69 were found to have twice the risk for non-insulin dependent diabetes as their physically active counterparts. It is suggested that for each additional 500 kcal of expenditure per week from physical activity, risk for non-insulin dependent diabetes is reduced by 6%. Additionally, more vigorous activities were associated with the greatest benefits. A study of 34-59 year old women who reported engaging in vigorous physical activity at least once a week experienced a reduction in risk by 16% compared to women who did not participate in vigorous activities.
Exercise has demonstrated an improvement in carbohydrate metabolism and glucose tolerance by enhancing the cellular uptake of sugar. Contracting muscle tissue likely causes a synergistic effect between insulin and cellular sensitivity, increasing glucose transport into the cell. Once carbohydrates make it into the cell, glucose can either be burned for immediate energy or stored as glycogen. The increased sensitivity to insulin prevents what is known as hyperinsulinemia, (a condition where there are excess levels of insulin circulating in the blood relative to the level of glucose), and improves glucose tolerance, providing a protective effect from the onset of the disease. Most of the cellular receptors for insulin are found on skeletal muscle. Of course that makes sense when you consider that skeletal muscle is very active and requires a lot of energy. If you keep your skeletal muscles healthy and strong, the muscles’ sensitivity to insulin will improve. The result will be optimal uptake of glucose from the blood. But if you lose muscle mass (a condition known as sarcopenia) and you get a little flabby, you could experience the opposite effect – reduced insulin sensitivity and a buildup of sugar in your blood. To overcome this, your body will produce more and more insulin. Over time this could have a dampening effect on your insulin’s effectiveness. This means that managing blood sugar for diabetics, even with drugs, could be way more difficult.
A great example of this occurred a few years back when I gained about 20 pounds. As a result of stressful events in my life, less physical activity, and increasing my insulin to compensate for my high blood sugars, the pounds just piled up. This is why insulin is known as the “fat storage hormone”. I was able to reverse the weight gain by again increasing my physical activity, first slowly and then more vigorously, which improved my bodies sensitivity to the insulin I was taking. Over a 9 month period I was able to reduce my insulin intake by nearly 25% and was able to shed the 20 pounds I had previously gained.
Please note: I have 42 years of experience with my diabetes and I monitor my blood sugars closely. Before beginning any exercise activity and insulin modification please consult your physician. Improving insulin resistance through muscle-toning resistance exercises may not work for obese people, as they seem to have different physiological responses to exercise than normal- weight people.
Both aerobic & resistance training can provide benefits.
Low cardiorespiratory fitness is a powerful and independent predictor of mortality in people with diabetes. Individuals with Type II diabetes are often at a greatest risk due to the presence of compounding factors, including dyslipidemia, (an abnormal amount of lipids, e.g. cholesterol and/or fat in the blood), obesity, and hypertension. Prolonged aerobic training performed at a moderate intensity has been shown to improve cardiorespiratory function in diabetics. In addition, participation in aerobic exercise demonstrates positive effects on visceral and subcutaneous adiposity (fat), insulin response, and plasma triglycerides levels (a type of fat (lipid) in your blood).
Resistance training yields similar, and in some cases more profound effects than aerobic training on diabetes. Compared to aerobic training, Type II diabetics who participated in 4 months of strength training significantly improved blood glucose levels and insulin resistance, reduced LDL (bad cholesterol) and triglycerides, and increased HDL (good cholesterol) above diabetic individuals who performed aerobic training for the same period of time.
When you combine aerobic and resistance activities in an exercise circuit, which is what I did during the 9 months I lost 20 pounds, you will see positive adaptations on glucose control, insulin action, muscular strength, and exercise tolerance. In addition, you should see your blood pressure reduced, skinfold and waist to hip measures significantly decreased, and fasting blood plasma glucose levels reduced. Also, your functional capacity, muscular strength, lean body mass, and glycemic control should all increase significantly. As you can see, it seems that both resistance training and aerobic training are necessary components to an effective exercise program for those with diabetes either performed independently of each other or combined in a circuit training program.
Physical activity has been shown to improve glucose management through muscle cell changes and fat cell response. Physical activity also leads to indirect benefits, including weight management, reduced central fat storage, and metabolic efficiency.
Resistance exercises are all about toning major muscle groups.
Adults should try to exercise each major muscle group two or three days a week using a variety of exercises and equipment. Very light or light intensity is best for older people or previously sedentary adults who are just starting to exercise.
Typically, two to four sets of each exercise will help you improve your strength and power. Here are the major areas to focus on:
Resistance exercises use relatively light weights and a high number of repetitions. For instance, 20 repetitions in 3 sets is a great way to improve muscle tone and endurance. Adults should typically wait at least 48 hours between resistance training sessions to rest and recover.
Circuit training is more advanced.
This should only be done by people already in an exercise program with approval from their doctors. Circuit training is a form of conditioning combining resistance training and high-intensity aerobics. It’s designed to be easy to follow and targets strength building as well as muscular endurance. An exercise “circuit” is one completion of all exercises in the program. When one circuit is complete, you begin the first exercise again for another circuit. Typically, the time between exercises in circuit training is short, often with rapid movement to the next exercise. Benefits of circuit training include:
• An effective means of improving strength endurance (or muscular endurance).
• May be easily structured to provide a whole body workout.
• May not require expensive gym equipment.
• Can be adapted for any size workout area.
• Can be customized for specificity; easy to adapt to your sport.
Also, individuals with advanced non-insulin dependent diabetes may experience complications with excessive physical activity, including ketosis, hyperglycemia (high blood sugar), and hypoglycemia (low blood sugar) responses to vigorous exercise.
As you can see physical exercise is a great benefit for diabetics and can greatly improve your overall health and fitness.