Sports Medicine with Dr. Jeffery MacLeod

THE ROLE OF EXERCISE IN PREVENTING AND MANAGING TYPE II DIABETES

Type II Diabetes accounts for 95% of Diabetes; it is a chronic disease in which the body cannot effectively utilize insulin, the hormone that regulates the metabolism of glucose. When the body cannot control glucose levels appropriately, the impact on health is alarming. One of the main effects is that both large and small blood vessels are damaged and, as every organ in the body relies on blood supply to function, an impaired blood supply results in damage to every organ in the body. Some of the first organs to be damaged include the kidneys, which results in renal failure and the requirement to artificially filter blood – a process known as dialysis; the retina, the part of the eye that registers light, damage to which leads to blindness; and, less well recognised, the penis, damage to which leads to early onset erectile dysfunction. As the disease progresses the heart is affected, leading to heart attacks and heart failure, and the blood vessels of the brain, leading to strokes. Diabetes UK estimates that type II Diabetes reduces life expectancy by up to 10 years, and quality of life in the last decades is significantly reduced as diabetics face dialysis, strokes, heart attacks and limb amputations.

The incidence of diabetes in Bermuda is particularly concerning. Among the world’s richest countries, Bermuda has the highest rates of diabetes, with approximately 13% of the population suffering from this disease, which is more than double the average among the OECD (Organisation for Economic Co-operation and Development) countries. Black Bermudians are even more impacted, among whom the incidence is around 16%. As a result, the incidence of renal dialysis and cardiovascular disease is disproportionately high and constitutes a huge burden on Bermuda’s health service funding.

The tragedy is that much of this burden is preventable. Significant preventable risk factors for Type II Diabetes are obesity, inactivity and a poor diet – factors entirely within our control. Even once diabetes develops, with attention to lifestyle factors the disease can often be managed such that blood glucose levels are kept within the normal, non-diabetic range – this is often referred to as “reversal”, although in truth the tendency for high blood glucose levels cannot be eliminated, even if the levels are well-controlled.

Diet is integral to both weight and glucose intake, so has double importance in the prevention and management of diabetes, and it is not rocket science. The obvious sources of sugars shouldn’t even need explaining – sodas, sweets, cakes and desserts, and these should clearly be avoided or minimised. However, the main source of glucose intake in most diets is not so obvious– carbohydrates. Carbohydrates, the main fuel we turn to when exercising, is broken down in the digestive tract to glucose and absorbed as such. And as the numerous low-carbohydrate diets

have demonstrated, they are the main source of calories for most people. If you run the risk of diabetes, therefore, carbohydrates need to be minimised.

Sources of carbohydrates tend to be our staples – bread, rice, pasta and potatoes. Additionally, almost all processed foods are high in simple carbohydrates. So when you think of diabeticfriendly diets, think natural. Avoid starchy and processed foods and, if you do eat them, go for the least processed options and smaller portions. White tends to be bad; brown or wholegrain rice, pasta and bread is better than white, and sweet potatoes are lower in carbohydrates than white potatoes. Likewise unprocessed meats such as fish, chicken and red meats are almost carbohydrate-free, whereas processed burgers, sausages and breaded nuggets etc., are high in both calories and carbohydrates. Fruits are often listed among unhealthy foods for diabetics because of their sugar content, however, the sugars in fruits are slow-release and they are both high in nutrition and low in calories so, along with other unprocessed foods, fruits feature in the healthy list.

Exercise is the other factor that impacts blood glucose levels – and far more than just the sugars that are immediately burned for energy. Evidence shows that exercise can increase skeletal muscle uptake of glucose fivefold by increasing glucose transport across cell membranes. As a result, exercise reduces blood sugar for up to 96 hours after the workout by making your body more sensitive to insulin. Furthermore, there is a long-term effect of regular exercise that results in increased insulin sensitivity and insulin responsiveness of skeletal muscle. Central to this, an enzyme which is the major insulin-dependent regulator of glucose uptake – adenosinemonophosphate-activated protein kinase or AMPK–is activated after exercise and has multiple effects on glucose, lipid and nutrient metabolism, mainly through muscle mitochondrial functioning and oxidation.

Exercise also impacts glucose metabolism and insulin-sensitivity in the pancreas, liver and adipose or fat tissue in a whole number of ways. Additionally, chronic, low-grade inflammation is also linked to diabetes and this again is improved by exercise, and can be tracked in the reduction of the pro-inflammatory marker, C Reactive Protein (CRP).

In summary, a disproportionate number of Bermudians are at high risk of developing Type II Diabetes and having both longevity and quality of life significantly reduced. Through multiple mechanisms exercise, both aerobic and anaerobic, cardiovascular and resistance training, are critical to reducing the risk of diabetes as well as managing or reversing it if it does develop.

FOR FURTHER READING:

https://www.diabetes.org

https://www.diabetes.org.uk

Hawley JA, Lessard SJ. Exercise training-induced improvements in insulin action. Acta Physiol (Oxf) 2008;192:127–135. [PubMed] [Google Scholar]

Kirwan JP, Sacks J, Nieuwoudt S. The essential role of exercise in the management of type 2 diabetes. Cleve Clin J Med. 2017 Jul;84(7 Suppl 1):S15-S21. doi: 10.3949/ ccjm.84.s1.03. PMID: 28708479; PMCID: PMC5846677.

Dr Jeff MacLeod Family Practice Group, Island Health Services MFSEM FRCGP MRCGP BMBS PGDip(SEM) MA BA(Hon)