By SAM SCOTT, Head of Research
Approximately 463 million people are currently living with diabetes worldwide, and this number is projected to reach 578 million by 2030 1. There are several types of diabetes with the two main classes being type 1 diabetes and type 2 diabetes. Type 2 diabetes accounts for about 90% of cases worldwide, of which 50% are treated by drugs with an associated risk for hypoglycaemia (mainly insulin). Type 1 diabetes is the most common endocrine condition in children and young adults 2, with an estimated 40 million individuals living with the condition worldwide 1.
Current guidelines for the management of both type 1 and type 2 diabetes recommend regular physical activity 3. The current guidelines for people with both type 1 and type 2 diabetes are to accumulate 150 minutes of moderate to vigorous intensity exercise per week, with no more than two consecutive days without activity. Resistance exercise is also recommended twice per week 3.
Regular physical activity is known to have a number of physical and psychological benefits. For example, exercise reduces body fat, decreases incidence of depression, and potentially reduces the long-term risk of macro-vascular (damage to large blood vessels) complications.
Type 1 Diabetes and Exercise
Regular exercise is accepted as a cornerstone for type 1 diabetes management and maintenance of overall health (Figure 1). However, exercise can represent a considerable challenge. An understanding of glucose targets for safe and effective exercise and the hormonal responses to different forms of exercise is important.
As with the rest of the population, current guidelines suggest that people with type 1 diabetes should perform at least 150 minutes of moderate-intensity or 90 minutes of vigorous-intensity physical activity per week with no more than two consecutive sedentary days 3.
Exercise can potentially lower or raise blood glucose 4. During exercise, blood glucose can lower due to the muscles using glucose as energy and the body can become more sensitive to insulin. However, sometimes blood glucose concentration increases due to other factors, for example, the effect of other hormones such as adrenaline that are also released during physical activity (Figure 2).
Everyone’s diabetes is different, and individuals react differently to exercise. It is important that people with diabetes understand how their blood glucose responds to exercise so they can manage these fluctuations and prevent hypoglycaemia or hyperglycaemia. Exercise must always be prepared for in advance, and insulin or food adjustments might be needed in order to stay within the optimal blood glucose range 4.
Type 2 and Exercise
Type 2 diabetes is often managed with a healthy diet and increased physical activity 1. The development of type 2 diabetes is associated with obesity, particularly abdominal obesity 5. People living with type 2 diabetes do not usually experience such pronounced blood glucose fluctuations as those living with type 1 diabetes, particularly if they have not progressed to insulin therapy and are still producing their own insulin.
Exercise can help people living with obesity and/or type 2 diabetes to lose weight and improve insulin sensitivity 6 7. People living with type 2 diabetes are recommended to accumulate 150 minutes of moderate to vigorous intensity exercise per week, with no more than two consecutive days without activity. Supervised and combined aerobic and resistance training may have additional health benefits. Persons with type 2 diabetes are also encouraged to increase their total daily unstructured physical activity.
Lessons from Team Novo Nordisk
Professional road cycling is one of the most physically demanding sports; combining extremes of exercise duration, intensity and frequency 8. Road cycling involves high training volume, long seasons with frequent competition days (60-100 per year), with races up to 6-8 hours and stage races ranging from 5 days to 3 weeks 8. Professional riders are required to regularly compete alongside multiple uncontrollable variables such as changing weather and road conditions, variable team tactics and different altitudes. This is compounded by tight race schedules, travel distances between race days, with frequent domestic and international flights.
An individual with type 1 diabetes wishing to compete in professional road cycling competitions has the monumental task of managing their blood glucose alongside challenges of the training and races. Team Novo Nordisk is the first professional cycling team to consist solely of people with diabetes and the riders manage their diabetes while training and competing at a professional level.
Team Novo Nordisk athletes work hard to manage their diabetes and work closely with the team doctor to find a regimen that works for them. Athletes closely monitor their blood sugar before, during and after the race, developing a deep understanding of how their body responds to exercise. They learn how to adjust their nutritional intake and insulin to stay within a safe blood glucose range.
If the athlete’s blood sugar is above target, they may adapt accordingly. If their blood sugar is below target, they may eat or drink something with carbohydrates. Everyone is different and it is important for individuals to work with a healthcare professional to find the method that works for them.
The achievements of Team Novo Nordisk demonstrate that as long as people are educated about their condition, and are disciplined and committed to managing their diabetes, with the help of experienced healthcare professionals, diabetes does not need to preclude them from intense physical activity and even endurance sports 9 10.
Just like the Team Novo Nordisk athletes, people with diabetes who want to progress from regular exercise to endurance sports, should speak to their healthcare professionals first and follow an individually designed training programme.
- IDF Diabetes Atlas 9th Edition. International Diabetes Federation, IDF Diabetes Atlas. Secondary International Diabetes Federation, IDF Diabetes Atlas 2019.
- Silink M. Childhood diabetes: a global perspective. Hormone research 2002;57 Suppl 1:1-5.
- Colberg SR, Sigal RJ, Yardley JE, et al. Physical Activity/Exercise and Diabetes: A Position Statement of the American Diabetes Association. Diabetes Care 2016;39(11):2065-79.
- Riddell MC, Gallen IW, Smart CE, et al. Exercise management in type 1 diabetes: a consensus statement. The lancet Diabetes & endocrinology 2017;5(5):377-90.
- Kahn SE, Hull RL, Utzschneider KM. Mechanisms linking obesity to insulin resistance and type 2 diabetes. Nature 2006;444(7121):840-6.
- Scott SN, Shepherd SO, Hopkins N, et al. Home-hit improves muscle capillarisation and eNOS/NAD(P)Hoxidase protein ratio in obese individuals with elevated cardiovascular disease risk. J Physiol 2019;597(16):4203-25.
- Little JP, Gillen JB, Percival ME, et al. Low-volume high-intensity interval training reduces hyperglycemia and increases muscle mitochondrial capacity in patients with type 2 diabetes. Journal of applied physiology (Bethesda, Md : 1985) 2011;111(6):1554-60.
- Lucia A, Hoyos J, Chicharro JL. Physiology of professional road cycling. Sports medicine (Auckland, NZ) 2001;31(5):325-37.
- McCarthy O, Eckstein ML, Scott SN, et al. Glycemic responses to strenuous training in male professional cyclists with type 1 diabetes: a prospective observational study. BMJ open diabetes research & care 2020;8(1).
- Scott SN, Christiansen MP, Fontana FY, et al. Evaluation of Factors Related to Glycemic Management in Professional Cyclists With Type 1 Diabetes Over a 7-Day Stage Race. Diabetes Care 2020;43(5):1142-45.