How can exercise prevent diabetes?
346 million (approximately 7 % of the world's population) people worldwide are estimated to have diabetes -a number that the World Health Organization (WHO) expects will double within the next 20 years. The paradox of this new epidemic is that it has been estimated that 80 % of all incidents of diabetes can actually be prevented if the primary risk factors were eliminated. Treatment and prevention of diabetes has a significant economic global impact.
Lykke Sylow is writing her PhD on insulin resistance at the Department of Nutrition, Exercise and Sport Sciences, Faculty of Science, University of Copenhagen. And we asked her to explain us about her research and why exercise can prevent diabetes
What is the role of insulin?
Insulin is a hormone which is released from the pancreas into the blood after a meal when blood sugar is high. When insulin is in the blood it is transported to various organs, such as adipose tissue, the liver and the muscles where it gives those organs a signal to take up the sugar so that blood sugar returns to normal.
Why do people become insulin resistant?
What happens when a person becomes resistant to insulin is that various organs, including the muscles which take up a very large proportion of the sugar after a meal, do not respond very well to the insulin that is released in the blood. This means that the muscles do not take up as much sugar and the level of sugar in the blood remains high. However, nobody knows exactly what causes insulin resistance.
Insulin resistance is commonly found in overweight and obese individuals, and is related to physical inactivity and low birth weight. There is also evidence showing that genetic factors can predispose a person to become insulin resistant. Insulin resistance is found in several diseases, the most common one being type 2 diabetes.
Why does insulin resistance increase the risk of type 2 diabetes?
When people are insulin resistant, their pancreas tries to compensate for this decreased responsiveness to insulin by producing more and more insulin to maintain normal blood sugar. However, in some insulin resistant people the insulin resistance eventually causes the pancreas to "burn out" and it loses the capacity to produce enough insulin. This leads to inability of the muscles, fat and liver to take up sugar from the blood and therefore the blood sugar concentration increases. When this happens the patient has developed type 2 diabetes.
Is insulin resistance a global health issue?
The numbers speak for themselves: 346 million (approximately 7 % of the world's population) people worldwide are estimated to have diabetes -a number that the World Health Organization (WHO) expects will double within the next 20 years.
For this reason treatment of diabetes has a significant economic global impact. For example, WHO estimates that in the period 2006-2015, China will spend 558 billion US dollars of national income due to diabetes related complications.
China, India and the USA are currently considered to be the diabetes capitals of the world. Studies have found, that one global factor in particular determine one's risk of developing diabetes; one's ethnicity. Type 2 diabetes is up to 6 times more likely in people of South Asian descent, and up to 3 times more likely in African and African-Caribbean people than in Caucasians. This picture is also evident in North America: black, Hispanic, Asian-American people, and Pacific Islanders are much more likely to have diabetes than white non-Hispanic, and American Indians are more likely than any other ethnic group in America to develop diabetes.
Since insulin resistance largely increase the risk of diabetes, insulin resistance is a huge global health issue, and diabetes is now recognized as a global epidemic with the potential to cause a worldwide health care crisis.
Can you treat or prevent insulin resistance?
One of the reasons that insulin resistance and diabetes are a huge and rapidly growing global problem is that people are becoming increasingly overweight and inactive. Thus, a healthy diet and regular physical activity to maintain a normal body weight can prevent or at least delay the onset of insulin resistance and type 2 diabetes. Exercise, just like insulin, increases the uptake of sugar from the blood into the muscles, thus lowering the blood sugar. This is beneficial to people with insulin resistance, since they have problems maintaining normal blood sugar. Also, insulin sensitivity is increased for up to 48 hours after exercise. This means that people, who have insulin resistance, will be able to "rescue" some of this sensitivity by exercising regularly.
Insulin resistance is most commonly treated with drugs. The most common drug is called metformin. However, the Diabetes Prevention Program showed that treatment with metformin only reduces the risk of developing diabetes by 31 %, whereas a lifestyle that combines exercise and a healthy diet can decrease the risk by 58 %. This is what I am working on. My PhD project investigates the underlying mechanisms of the positive effects of exercise in terms of preventing insulin resistance, since large scale studies show that exercise alone can prevent and to some extent reverse diabetes.
Why do you work with this area?
I have always liked to exercise myself, and find it fascinating how exercise has a beneficial effect on almost all the body`s physiological functions, including preventing various diseases. I am investigating the molecular events regulated by exercise and how these regulatory mechanisms can improve insulin sensitivity. Understanding these mechanisms is very important, as it might provide us with knowledge about how to treat and prevent insulin resistance and diabetes, which have huge global personal, social and economical implications.
How do you hope your research can make a difference?
I hope that by getting a better understanding of why we become insulin resistant, we will do better to prevent and treat insulin resistance and thereby prevent the diabetes epidemic. The paradox of this new epidemic is that it has been estimated that 80 % of all incidents of diabetes can actually be prevented if the primary risk factors were eliminated. Despite this, the burden of insulin resistance and diabetes are growing - the number of people, families and communities afflicted are increasing. I believe that insulin resistance and diabetes largely can be prevented by taking comprehensive and integrated action at country level, led by governments. Research in this area will help governments, societies, individuals and health professionals to take the right turns on the road to remove insulin resistance and diabetes from the map of major global health issues in the future.