Can Physical Activity Help Diabetes?

What is Diabetes Mellitus?

• Diabetes Mellitus (DM) occurs when blood glucose is poorly controlled. 
• Type 1 diabetes mellitus (TIDM) is caused by an autoimmune process that damages insulin-secreting cells of the pancreas. This damage causes low insulin. Insulin pulls glucose out of the bloodstream and into cells for energy and storage. Low insulin levels can contribute to hyperglycemia in the blood.
• Type 2 diabetes mellitus (T2DM) is caused by insulin resistance related to prolonged elevated blood sugar, genetics, lifestyle, and diet (2). T2DM makes up more than 90% of all diabetes cases. 
• Prediabetes impacts over 98 million people or over 1/3rd of the US. DM impacts over 10% of the US and is also the 7th leading cause of death in the US (2).

Signs and symptoms 

• Diabetes is associated with sleep deprivation because one night of poor sleep can reduce insulin sensitivity.
• Prolonged hyperglycemia can cause glycation in blood vessels, the retina, nerves, and other organs. This can lead to blindness and other eye-related problems.
• Diabetic neuropathy is nerve damage that can occur in the feet and other organs. It can occur due to elevated blood glucose damaging the blood vessels and nerves (6). Peripheral neuropathy can impact the feet and legs and cause reduced sensation and balance. 
• Hypoglycemia of blood glucose <70 mg/dL can make you feel faint, dizzy, irritable, weak, shaky, or sweaty. Hypoglycemia can also cause seizures and loss of consciousness (7)
• Urinary frequency, excessive thirst, and hunger may be seen in DM. 

Physical activity

An active lifestyle may include walking, gardening, errands, and an active job.

• Movement helps regulate blood glucose by burning energy. Additionally, activity can reduce cardiovascular risk factors, assist in weight loss, and increase physical and mental health (3). Regular activity may prevent or delay T2DM development (3). 
• Those with diabetes are encouraged to be active throughout the day. For instance, sitting should be interrupted every 30 minutes for a light activity to help regulate blood glucose (3). Postmeal walks, gardening, or errands for 3-15 minutes can improve glycemic control (3). 
• A pedometer is a step counter. Aim to achieve the goal of >7500 steps per day and avoid taking less than <5000 steps/day (1). 

Aerobic Exercise

Continuous movement of large muscle groups such as rowing, walking, swimming, and running.

Purpose:

• During exercise, glucose is pulled out of the blood and into skeletal muscle with and without the use of insulin (1). Aerobic exercise can increase glucose uptake into the muscle by up to 500% in the short term (3). 
• Insulin sensitivity can improve after exercise for 2-72 hours (1). Aerobics can improve insulin resistance, lipids, and endothelial function in T1DM (3). 
• Aerobics can improve triglycerides, blood pressure, and insulin resistance in T2DM (3).
• Aerobic exercise can decrease HbA1C by .5-.7% (1). 
• After aerobic exercise, glucose remains elevated independently of glucose for 2 hours, and dependent on glucose for 48 hours in a process to refuel glycogen stores in the muscle.
• Exercise of at least 150 minutes a week improves glycemic control in T2DM (3).

Intensity:

• (HRMax-HRrest) x (40-70%) + HR rest
• Moderate: 
  • Rating of Perceived Exertion (RPE) 3-4/10 where 0 is resting, and 10 is very very hard.
  • Can use 40-59% VO2R or HRR. (HRMax-HRrest) x (40-59%) + HR rest
• Vigorous
  • RPE of 5-8.
  • Can also use 60-89% VO2R or HRR. (HRMax-HRrest) x (60-89%) + HR rest
• Moderate-intensity aerobic training can reduce symptoms of insomnia.
• Low-intensity aerobic training of >60 minutes can improve the function of insulin in obese insulin-resistant adults for 24 hrs (3).

Duration

• A minimum of 10 minutes, with the goal of 30 minutes (1).
• Warm up for 5-10 min, perform 10-60 minutes of aerobics, and cool down for 5-10 min.
• If feasible, progress the total volume to 150 minutes a week of moderate-intensity (1). Additionally, those able to safely perform 75 minutes a week of vigorous activity, should do so.

Frequency:

• Most days of the week 3-7 days per week (1).

Progression

• If fitness is the goal, an emphasis on vigorous intensity exercise if there are no contraindications.

Resistance Exercise

Exercise with free weights, body weights, machines, and elastic bands.

Purpose:

• Resistance exercise can help manage glucose while blunting insulin response, particularly high-intensity resistance if safe to do so.
• Resistance exercise can result in 10-15% improvements in strength, bone mineral density, lipid profile, and insulin sensitivity. 
• DM is a risk factor for reduced muscle strength and a decline in function and strength training can help combat this loss (3).

Repetitions

• 6-8 for vigorous and 15 repetitions for moderate intensity. Progress from 1 set to 3 as tolerance improves. 

Activities

• Exercise which works major muscle groups such as squats, planks, deadlifts, and rows. 

Frequency

• 2-3 days each week.
• At least two nonconsecutive days each week.

Progression

• Progression of sets, reps, weight, and training frequency can be done as safe to do so.

Combined exercise

An exercise program with a combination of both aerobic and resistance training may produce optimal glycemic and health outcomes in T2DM(3).

• A greater reduction in HbA1C was achieved with combined training. Combined exercise may also aid in efforts to lose weight.
• Exercise has been shown to help T1DM increase strength, cardiovascular fitness, and insulin sensitivity (3). 
• Children and adolescents with T1&2 DM should participate in 60 minutes/day of moderate or vigorous activity that strengthens their muscles and bones at a minimum of three days per week (1).
• Daily exercise, or at least never taking more than 2 days to exercise again can improve insulin sensitivity (3).

High-Intensity Interval Exercise HIIE

Purpose:

• Improved A1C, CVD risk, stroke volume, ejection fraction, and endothelial function (1). Improved oxidative muscle capacity, insulin sensitivity, and glycemic control in T2DM (3).
• One session of 10 reps x 60-second cycling at 90% MHR reduced postprandial hyperglycemia in type 2 diabetes.
• Two weeks of afternoon HIIE may improve continuously monitored glucose.

Intensity

• Training between 65-90% VO2 Max or 75-95% HRMax for 10 sec to 4 min with 12 sec to 5 min of rest.
• A high intensity and low duration of <10 minutes may increase blood glucose (3). Therefore, those with very high blood glucose should consult a healthcare professional before initiating exercise. The safety and efficacy of HIIE are unknown in those with DM, and it should only be performed in those who are medically stable. 

Flexibility

Use of a full range of motion statically and dynamically of joints. Flexibility exercise can improve and maintain range of motion around joints (3).

Activities: Individual flexibility program or group classes such as yoga and tai chi. 

Intensity: Stretch until moderate discomfort is felt in the target muscle.

Duration: Hold for 10-30 seconds for 2-4 reps.

Frequency: 2-3 days or as needed. 

Balance

Peripheral neuropathy can impact the sensation of an individual with DM. The inability to feel the ground can increase fall risk. Activities such as tai chi, resistance training, yoga, and physical therapy, can reduce fall risk (3).

Frequency: 2-3 days or as needed

Prevention

• Activity was inversely related to T2D for all participants. Moderate-intensity walking of 18.2 km/week improved oral glucose tolerance with 2kg weight loss (1).
• PA of 150-175 min/week and weight loss of 5-7% reduced the risk of developing T2DM in people with impaired glucose tolerance by 40-70% (3).
• The CDC has a national diabetes prevention program that boasts a 58% reduced risk of developing T2DM from prediabetes.  

Diet and Weight loss

• For every 1 kg bodyweight lost, there was a 16% reduced risk of T2D.
• Through changes in diet and physical activity. A loss of >5% body weight may improve A1C, blood lipids, and blood pressure (1).
• To lose fat, 500 kcal of exercise done 4-5 days a week is recommended (1). In high-risk populations, weight loss of 5-7% is recommended to prevent or delay T2DM progression (3).

Medical Considerations 

Physical activity carries risks for individuals with DM. It is recommended that those who wish to participate in higher intensity activity consult with a health care professional who can provide appropriate activity and disease management. 

Retinopathy

• Avoid forceful head movements and hard straining to prevent bleeding of small blood vessels in the eye. Keep the head above the hips to avoid exposing the eyes to high blood pressure.
• Do not allow SBP to increase >30 mmHg above resting, avoid powerlifting.

Hypertension

• Can be a significant comorbidity in DM. The ADA recommends a goal of 130 mmHg systolic and 85 mmHg diastolic blood pressure if elevated (2). 

Post-exercise hyperglycemia

• Those who chronically train may have transient postexercise hyperglycemia, especially in those who perform high-intensity exercise.

Diabetic Ketoacidosis (DKA)

• This can occur when there is insufficient insulin to bring glucose into the cells, so the cells need to use protein and fat for energy which produces ketones. Ketone production can be acidic to the body. More common in T1DM. Symptoms are confusion, fast heart rate, fever, and changes in how the breath smells. DKA can also cause vomiting and electrolyte imbalance and can be life-threatening (2). If ketones >1.5 mmol/L, consider a trip to the doctor and exercise hold off on exercise (1).

Peripheral Neuropathy

• Check the skin for ulcers. Due to lack of feeling, be wary of creating fractures in the legs and feet with high-impact activities

Blood glucose and exercise (3)

• If glucose is <90 mg/dL, ingest 15-30 g of carbohydrates depending on intensity and duration (3). Consult with the health team if below <100 mg/dL of glucose.
• If 90-150 mg/dL, consume .5-1g/kg of carbohydrate per hour of exercise depending on intensity and insulin.
• If 150-250 mg/dl, exercise without additional carbohydrate until blood glucose is <150 mg/dL.
• If 250-350 mg/dL, test for ketones. If a moderate-large quantity of ketones is present, do not perform the exercise until <250 mg/dL. This is because exercise, especially at high intensity may exacerbate the hyperglycemia.
• If >350mg/dL test for ketones and do not initiate if present. If no ketones, consider insulin to correct before exercise (3). 
• During exercise, and after insulin injection, carbohydrates of 30-60 grams may be needed during low to moderate exercise to prevent hypoglycemia (3).
• When insulin is low during moderate exercise, 10-15 grams of carbs can be taken (3). During exercise, a reduction in insulin dose may be considered to prevent hypoglycemia (3).

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Disclaimer: 

This content is for educational purposes only and does not constitute the practice of physical therapy, nursing, or other professional health care services, including the giving of medical advice, and no doctor/patient relationship is formed. Using information or materials for any reason is at the user’s risk. This content is not a substitute for professional medical advice, diagnosis, or treatment. Users should not disregard or delay in obtaining medical advice for any medical condition they may have and should seek the assistance of their healthcare professionals for any such conditions.

Physical activity prescription should be tailored to each individual based on their age, DM type, activity level, and comorbidities by a health professional.

References:

1. Kanaley, J. A., Colberg, S. R., Corcoran, M. H., Malin, S. K., Rodriguez, N. R., Crespo, C. J., Kirwan, J. P., & Zierath, J. R. (2022). Exercise/Physical Activity in Individuals with Type 2 Diabetes: A Consensus Statement from the American College of Sports Medicine. Medicine and Science in Sports and Exercise, 54(2), 353–368. https://doi.org/10.1249/MSS.0000000000002800
2. Sapra, A., & Bhandari, P. (2024). Diabetes. In StatPearls. StatPearls Publishing. http://www.ncbi.nlm.nih.gov/books/NBK551501/
3. Colberg, S. R., Sigal, R. J., Yardley, J. E., Riddell, M. C., Dunstan, D. W., Dempsey, P. C., Horton, E. S., Castorino, K., & Tate, D. F. (2016). Physical Activity/Exercise and Diabetes: A Position Statement of the American Diabetes Association. Diabetes Care, 39(11), 2065–2079. https://doi.org/10.2337/dc16-1728
4. CDC. (2021, December 21). Prediabetes—Your Chance to Prevent Type 2 Diabetes. Centers for Disease Control and Prevention. http://bit.ly/2hMpYrt
5. https://www.cdc.gov/diabetes/prevention/index.html
6. Diabetic Neuropathy—NIDDK. (n.d.). National Institute of Diabetes and Digestive and Kidney Diseases. Retrieved March 9, 2024, from https://www.niddk.nih.gov/health-information/diabetes/overview/preventing-problems/nerve-damage-diabetic-neuropathies
7. Low Blood Glucose (Hypoglycemia)—NIDDK. (n.d.). National Institute of Diabetes and Digestive and Kidney Diseases. Retrieved March 9, 2024, from https://www.niddk.nih.gov/health-information/diabetes/overview/preventing-problems/low-blood-glucose-hypoglycemia
8. CDC. (2018, August 21). All About Your A1C. Centers for Disease Control and Prevention. https://bit.ly/2Nc2IA0