Exercise can play a key role in managing diabetes in several different ways such as improved glucose uptake, improved insulin sensitivity, and increased glucose tolerance. The American Diabetes Association recommends those with prediabetes or diabetes get at least 150 minutes of moderate-intensity or 90 minutes of vigorous exercise per week. Ideally, this is at least 30 minutes 5 days per week. Let’s look more closely at how exercise can help manage pre-diabetes and type 2 diabetes.
Exercise can help improve glucose tolerance. Impaired glucose tolerance is a prediabetic state as it lies between normal glucose tolerance and diagnosed diabetes. Basically, if you have impaired glucose tolerance, you are in a prediabetes stage and vice versa. Several studies are showing that high intensity interval training (HIIT) can most markedly improve glucose tolerance.1-2 One particular study found that two hour oral glucose tolerance testing significantly improved after eight weeks of HIIT training done three times per week for a maximum time of 30 minutes.1
Exercise of any type can help improve glucose uptake in the muscle. In type 2 diabetes, the body usually releases plenty of insulin, but muscle, liver and fat cells do not respond to the insulin very well. This is called insulin resistance. When this happens, the transport of glucose into the cell is compromised. Exercise can help improve this glucose transport problem by upregulating signaling mechanisms that control the transport of glucose from the blood into the cell for use even without the help of insulin.3 Insulin also increases activity of glucose transporters, however insulin and muscular contraction use different pathways to improve glucose transport.4
Finally, exercise can also help increase insulin sensitivity. Post-exercise, insulin sensitivity may increase due to increased action and mobilization of glucose transporters to the cell surface.5 At this time, insulin has the opportunity to transport glucose at a more substantial rate and therefore improve circulating glucose levels. The effect of a single bout of aerobic exercise on insulin sensitivity lasts 24–72 hours depending on the duration and intensity of the activity.4,6 Therefore, it is recommended that aerobic exercise be done at least every two days to maximize exercise effect on glucose control.5
Overall, your current fitness level should determine your approach to improving your insulin sensitivity, glucose uptake, and glucose tolerance. Sedentary individuals will benefit from modest exercise intensities and frequencies, however those who are already physically active will benefit more from higher exercise intensity such as HIIT training combined with resistance training.5 An optimal exercise program would include at least two days of resistance training, two days of moderate intensity exercise for at least 45 minutes, and two days of high intensity intervals for 20-30 minutes per week.5 It is recommended that patients with type 2 diabetes consult their physician before starting any new exercise program.7
Resources:
- Madsen SM, Thorup AC, Overgaard K, Jeppesen PB. High intensity interval training improves glycaemic control and pancreatic β cell function of type 2 diabetes patients. PLoS ONE. 2015;10(8):e0133286.
- Rogers MA, Yamamoto C, King DS, Hagberg JM, Ehsani AA, Holloszy JO. Improvement in glucose tolerance after 1 wk of exercise in patients with mild NIDDM. Diabetes Care. 1988;11(8):613-618.
- Martin IK, Katz A, Wahren J. Splanchnic and muscle metabolism during exercise in NIDDM patients. Am J Physiol Endocrinol Metab. 1995;269(3 Pt 1): E583-E590.
- Holloszy JO. Exercise-induced increase in muscle insulin sensitivity. J Appl Physiol. 2005;99(1):338-343.
- Colberg SR. Why Enhancing Insulin Action with Physical Activity is Critical to Preventing, Reversing, and Controlling Type 2 Diabetes and Pre-Diabetes. https://insulitelabs.com/articles/enhancing_insulin_action.html.
- Quinn K. Duration of Improved Insulin Sensitivity After High Intensity Exercise in Young Overweight Men [dissertation]. Ames, IA: Iowa State University; 2015.
- Wallberg-Henriksson H, Rincon J, Zierath JR. Exercise in the management of non-insulin-dependent diabetes mellitus. Sports Med. 1998;25(1):25–35.