Lecturer and Lead Sport and Exercise Scientist at St Mary’s University, Paul Hough, has written an article on physical activity and diabetes. Paul’s twitter handle is: @the_hough
Introduction
Before discussing what diabetes is and how it can be prevented and treated, it is essential to introduce a hormone called insulin. Insulin is secreted from cells within the pancreas and plays a number of roles in the body’s metabolism; in particular, insulin affects how the body uses and stores glucose. Insulin helps control blood glucose levels by signalling the liver, muscle and fat cells to absorb glucose from the blood. In essence, insulin ensures that blood glucose levels remain within a healthy range (4.0 to 5.9 mmol/L before meals). If blood glucose levels remain elevated for long periods of time (hyperglycaemia) this poses a number of health risks, such as heart disease and nerve damage.
Type 1 diabetes
Type 1 diabetes develops when cells in the pancreas are unable to produce insulin. This form of diabetes is less common than type 2 diabetes, accounting for approximately 10% of all adults with diabetes. Type 1 diabetes is treated by daily insulin doses – taken either by injections or via an insulin pump.
Type 2 diabetes
Type 2 diabetes develops when the insulin-producing cells in the pancreas do not produce enough insulin, or when the sensitivity of the body’s cells to insulin are reduced – this is known as insulin resistance. A leading factor in the development of insulin resistance is obesity, particularly central obesity (excessive fat around the abdomen). Hence why it is important to keep body fat levels within a healthy range. Insulin resistance is a key factor in type 2 diabetes. Therefore, the same risk factors for developing type 2 diabetes generally apply for insulin resistance:
- Poor quality ‘Western’ diet: high consumption of processed foods containing high levels of trans fats and refined carbohydrates
- A sedentary lifestyle: lack of regular physical activity
In the UK, 3.5 million people are diagnosed with diabetes and it is estimated that 549,000 people have undiagnosed diabetes (diabetes.org.uk). The global prevalence of diabetes is predicted to reach nearly 600 million cases by 2035, which presents a substantial morbidity and mortality burden as well as huge financial cost implications to healthcare services (International Diabetes Federation, 2015).
Physical activity
The benefit of aerobic physical activity (PA) for preventing type 2 diabetes is well established. Regular engagement in aerobic PA (walking, running, cycling etc.) are associated with substantially lower risk of developing type 2 diabetes (Hu et al., 2003). Indeed, a recent study indicated that individuals who meet the recommended PA guidelines of 150 min/week have a reduced risk of developing type 2 diabetes equal to 26% relative to completely inactive individuals (Smith et al., 2016). Regular PA has also been demonstrated to be an effective treatment for patients with type 2 diabetes* (Sigal et al., 2007).
*Patients with diagnosed diabetes should consult their healthcare professional before engaging in a PA programme.
How much and what type of physical activity?
Aerobic activities
Adults should perform
150 minutes per week of moderate aerobic based PA. For example, walking, jogging, cycling, and swimming.
Alternatively, adults should engage in 75 minutes vigorous PA per week. Vigorous PA is performed an intensity where breathing becomes heavy and it is difficult to maintain a conversation. This type of PA also causes a sharp increase in heart rate and heavy sweating.
Resistance training
Regular muscular strengthening exercises, such as resistance (strength) training, is also associated with a reduced risk of type 2 diabetes. This is because resistance training promotes adaptations in muscle tissue, such as improving insulin sensitivity. Resistance training is also excellent for improving strength and maintaining muscle mass, both of which decline with ageing.
- To achieve the health benefits of resistance training, 2 sessions per week are recommended.
- Alternatively, 2-3 resistance exercises can be performed on a daily basis, which should take no longer than 10 minutes.
Barriers to regular physical activity
I don’t have time!
A lack of time is one of the most commonly cited barriers to performing regular PA. It is useful to remember that PA does not have to be performed in a gym and can be incorporated into a daily routine. Here are some examples:
- Active commuting: walking or cycling to work. If you need to drive or use public transport park a 10 minute walk from work or get off a few stops early on the train.
- Walking meetings: instead of sitting down to meet people, go for a walk during the meeting. This improves mood and creatively and often leads to more productive (and less mundane) meetings.
- Regular breaks: instead of sitting down for a coffee, head outside and go for a 10-15 minute walk.
- Use stairs instead of lifts and escalators.
I am not a member of a gym
Resistance training includes any type of exercise where the muscles work against a resistance. Therefore, body-weight exercises, such as squats and press-ups, can be performed at home. Alternatively, a number of exercises can be performed with inexpensive equipment such as
resistance bands or a
kettlebell.
Summary
Regular aerobic PA and resistance training are highly effective in improving blood glucose control and consequently the prevention and treatment of type 2 diabetes. Therefore, a combination of both aerobic PA and resistance training, performed on a weekly basis are recommended (Sigal et al., 2007).
Although regular PA is an effective strategy for the prevention and treatment of type 2 diabetes, research indicates regular PA performed alongside a healthy diet (minimally processed foods, low in sugar) is the most effective strategy for decreasing diabetes incidence and improving cardiovascular health.
References
Balk, E.M., Earley, A., Raman, G., Avendano, E.A., Pittas, A.G., & Remington, P.L. (2015). Combined Diet and Physical Activity Promotion Programs to Prevent Type 2 Diabetes Among Persons at Increased Risk: A Systematic Review for the Community Preventive Services Task Force.
Annals of Internal Medicine, 15, 437-451.
Hu, F.B., Li, T.Y., Colditz, G.A., Willett, W.C., & Manson, J.E. (2003) Television watching and other sedentary behaviors in relation to risk of obesity and type 2 diabetes mellitus in women.
JAMA 289, 1785–1791.
International Diabetes Federation (2015) IDF diabetes atlas, 7
th edition. International Diabetes Federation, Brussels.
Sigal, R.J., et al. (2007). Effects of aerobic training, resistance training, or both on glycemic control in type 2 diabetes: a randomized trial.
Annals of Internal Medicine, 18, 357-369.
Smith, A.D., Crippa, A., Woodcock, J., & Brage, S. (2016). Physical activity and incident type 2 diabetes mellitus: a systematic review and dose–response meta-analysis of prospective cohort studies.
Diabetologia. DOI 10.1007/s00125-016-4079-0
