The prevalence of type II diabetes is on a sharp rise in developed countries. According to Diabetes UK, over 3.5 Million people have been diagnosed with diabetes in the UK in 2015, and it is estimated that another half a million individuals have not been diagnosed yet. This means that 6% of the UK population is diabetic.
In Malta, rates are even higher. It is estimated that 10% of the adult population suffers from type II diabetes, according to Department of Health Information and Research, 2008.
Although genetics may play some part in the likelihood of developing diabetes, the condition is mainly a result of unhealthy lifestyle factors that include poor diet, lack of physical activity and smoking.
Diabetes is a serious health condition that can lead to heart disease and stroke, nerve damage, resulting in amputation of limbs, blindness, kidney failure and death. For national health services, the cost of treatment is a huge financial burden. In Malta, the average length of stay in hospital for diabetes was 13.7 days in 2011.
Insulin is the primary hormone responsible for lowering blood sugar (glucose) levels following a meal. The action of insulin allows glucose to move from the bloodstream into the peripheral cells of our body, where it is used for energy or stored as an energy reserve. When blood glucose levels are chronically elevated due to continuous ingestion of carbohydrates, insulin levels too become chronically elevated. As a result, the body develops an insensitivity to the action of insulin (insulin resistance), and blood glucose cannot be cleared efficiently from the blood stream any longer.
Lifestyle modification, in the form of dietary changes and increased physical activity, can have a significant positive effect in moderating, delaying or even reversing type II diabetes. Since type-II diabetes occurs predominantly in overweight or obese individuals, weight-loss is a primary objective in the treatment of type-II diabetes. Weight-loss not only helps to improve blood glucose levels, but also has positive effects on blood lipids (cholesterol and triglycerides) and blood pressure, all of which are considered cardiovascular risk factors.
Effect of exercise on diabetes
Exercise has a powerful effect on blood glucose control and is more powerful in controlling blood sugar than certain diabetes medications (Metformin). Contracting muscles increase the uptake of blood glucose. How much glucose is taken up depends on the intensity and the duration of the exercise performed. In diabetic patients, the rate of glucose uptake by muscle is diminished, however contracting muscles can also take up glucose from blood by other glucose-transporting means, which are not impaired by type 2 diabetes.
Most doctors generally recommend moderate intensity aerobic exercise such as walking or swimming as the activity of choice for diabetic patients, however some evidence suggests that a combination of resistance training and aerobic training produces better blood glucose regulation than either form of exercise on its own. Resistance training increases lean muscle mass and some studies have shown that increases in lean mass are related to decreases in HbA1c, a blood marker for mean blood glucose concentrations over a 2-3 month period, based on the hypothesis that increased muscle tissue enhances the storage capacity of glucose in the form of glycogen. Whether this is due to increased muscle size or improved qualitative muscle function is not entirely clear.
Obese individuals are often found to have higher levels of fat stored within muscle cells, known as intramuscular fat. Such fat deposits have been shown to lead to insulin resistance, a precursor of diabetes. Ironically, highly trained endurance athletes also show elevated levels of intramuscular fat, however, without the negative side effects of insulin resistance. The intramuscular fat deposits found in athletes are thought to serve the purpose of an immediate energy source for athletes during physical activity. Endurance athletes, by nature are highly insulin sensitive. This phenomenon is referred to as the athlete’s paradox, and shows how regular exercise can alter the body’s ability to process sugar.
Acute vs chronic exercise
The great news is that you don’t need to engage in an exercise programme for months in order to experience any positive effects on blood sugar clearance. Even a single bout of exercise can improve blood sugar clearance in diabetic individuals for up to 24 hours. However for long-term health benefits, it is necessary to exercise on a regular basis.
Both the American Diabetic Association (ADA) as well as the American College of Sports Medicine (ACSM) recommend aerobic exercise and resistance training as a treatment for diabetic patients that do not have contraindications to exercise. The recommendations are to perform moderate intensity aerobic exercise for at least 150 minutes per week and to complete 2-3 sessions of resistance training per week, using exercises that target the major muscle groups in the body. Increased intensity or additional volume of training can produce greater benefits.
This article appreared in the First Magazine with the Malta Independent on Sunday on 21st April, 2019.
MSc Nutritional Medicine