According to the Centers for Disease Control and Prevention (CDC), over 29 million people in the United States have diabetes - a condition where the body either doesn't make enough insulin (type 1 diabetes), or is unable to use insulin properly (type 2 diabetes).
Insulin is a hormone, made in the pancreas, which regulates blood sugar (glucose) levels, and allows the body to use glucose for energy.
Exercise can help reduce complications of diabetes including:
- Heart disease and stroke
- Blindness and other eye problems
- Kidney disease
- Amputations caused by damage to blood vessels and nerves, leading to infection
A further 86 million people have prediabetes - a health condition that increases their risk of developing type 2 diabetes and other illnesses.
Contents of this article:
Exercise and diabetes
Aerobic exercises such as brisk walking and hiking may help to manage the onset of diabetes symptoms.
Preventing the onset of diabetes for those with prediabetes, or managing symptoms for those who already have the condition, is crucial to maintain health and prevent complications. Exercise is one proven way to help manage diabetes.
According to a joint position statement by The American College of Sports Medicine and the American Diabetes Association, exercise:
- plays a key role in preventing and controlling blood sugar levels
- can prevent or delay type 2 diabetes
- can prevent diabetes during pregnancy (gestational diabetes)
Staying physically active also helps prevent diabetes-related health complications and improves overall quality of life.
Exercise is useful for those with diabetes because it improves insulin sensitivity by helping the cells of the body use available insulin. Physical activity also stimulates a separate mechanism, unrelated to insulin, to allow the cells to use glucose for energy, thereby regulating blood glucose levels.
Types of exercise for people with diabetes
The American Diabetes Association recommends two types of physical activity for those with diabetes: Aerobic exercise and strength training.
Also known as cardiovascular exercise, aerobic activity helps the body use insulin more effectively. It brings other benefits too, including:
- stress relief
- improved circulation
- reduced risk of heart disease
- lower blood pressure
- improved cholesterol levels
- strong bones
- weight management
- better mood
Examples of aerobic exercises include:
- brisk walking or hiking
- low-impact aerobic exercise classes
- Tai Chi
How much aerobic activity is needed?
The President's Council on Fitness, Sports and Nutrition recommends:
- 30 minutes daily of moderate physical aerobic activity
- at least 5 times weekly
This recommendation is for adults aged 18-64. Adults with diabetes should also aim to meet this target.
Those with a busy schedule may find it helpful to do several shorter workouts totaling 30 minutes daily - research suggests that the benefits received are similar to those associated with one longer workout.
Blood sugar levels may be reduced by strength training, such as using free weights.
Strength training, or resistance training, helps lower blood sugar levels and increases insulin sensitivity. In addition, it increases resting metabolism and builds stronger bones and muscles, reducing the risk of osteoporosis.
Examples of strength training include:
- lifting free weights
- lifting heavy objects, such as bottles of water or canned food
- weight machines
- resistance bands
- exercises that use body weight such as sit-ups, squats, planks, and push-ups
- strength training classes
How much strength training is needed?
Strength training should be undertaken at least twice a week, in addition to the recommended amount of aerobic activity.
Stretching exercises are important for everyone, including those with diabetes. Stretching:
- reduces the risk of injury from aerobic exercises or strength training
- increases flexibility
- prevents muscle soreness
- lowers stress levels
Incidental physical activity
It can be useful to consider incidental physical activity - everyday activities that aren't classed as exercise but involve movement. Some research suggests that such activities can contribute to improved fitness.
Types of incidental physical activities include:
- taking the stairs instead of the elevator
- walking to the bus stop
- moderate intensity gardening
- walking around the shopping mall
- washing the car
Monitoring blood glucose levels when exercising
To exercise safely, many people with diabetes - particularly those with type 1 diabetes or those on diabetes medications - may need to check their blood glucose levels before, during, and after exercise.
This indicates how well the body is responding to exercise, and may help avoid blood sugar fluctuations, which can be dangerous.
Testing blood glucose before, during, and after exercise
Blood sugar levels should be tested 30 minutes before exercise. If they are:
- Lower than 100 milligrams per deciliter (mg/dL) - blood sugar may be too low to exercise. Low blood sugar is known as hypoglycemia.
- Between 100 and 250 mg/dL - this is the optimal range, within which it is safe for most people to begin exercising.
- 250 mg/dL or higher - blood sugar may be too high to exercise. Carry out a urine test for ketones (which indicate more insulin is needed to control blood sugar). This is generally only a concern for those with type 1 diabetes.
During exercise, particularly long workouts or new activities, blood sugar levels should be tested every 30 minutes. Stop exercising if any of the following signs are there:
- blood sugar falls below 70 mg/dL
After exercise, check blood sugar levels immediately. Recheck levels several times over the following day - physical activity can lower blood glucose for up to 24 hours.
Hypoglycemia and exercise
If hypoglycemia (low blood sugar) is experienced during or after a workout, it should be treated immediately. This involves taking at least 15-20 grams of fast-acting carbohydrate such as:
- a sports drink
- regular soda
- glucose gel
- jelly beans
Blood glucose levels should be tested after 20 minutes, and the treatment repeated if they haven't returned to normal. Follow the fast-acting carbohydrates with a protein such as peanut butter and crackers. Do not resume exercise until blood glucose returns to above 100 mg/dL.
If hypoglycemia occurs regularly during exercise, it may be necessary to adjust medications or the exercise regimen, or to simply eat a small snack before working out. Skipping meals, strenuous exercise, or prolonged workouts can all cause hypoglycemia.
It should be noted that people with type 1 diabetes are more likely to experience hypoglycemia during or after exercising, although people with type 2 diabetes may have issues if they are on medication for their condition.
When to see a doctor
For people with diabetes, it is recommended to consult with a healthcare professional before any exercise programme commences.
It is advisable to consult a doctor before beginning any new workout program.
A doctor can advise on the impact of medications on blood sugar levels during activities, and can provide a target range for blood glucose levels during workouts. They may give advice on the best time to exercise, based on the patient's individual schedule, meal plan, and medications.
A doctor may also perform a physical check-up, looking at:
- heart health
- blood pressure
- diabetes-related complications
Depending on these complications, it may be advisable to avoid strenuous activities, or specific sports.
It is also important to consult a doctor if hypoglycemia is experienced regularly during or after exercise, or if any other undesirable side effects are experienced.
Beginning an exercise plan can be daunting. It is important to:
- Set realistic goals - start slowly - with just 5-10 minutes of exercise daily - and gradually increase the frequency and intensity of the activity.
- Include aerobic and strength-based activities - an exercise plan for diabetes management should include both aerobic exercise and strength training - research indicates undertaking both forms of physical activity is more effective than doing just one of the two.
- Take precautions - always keep fast-acting carbohydrates on-hand in case of hypoglycemia. Consider wearing a medical alert bracelet in case of emergency.
- Choose footwear wisely - many people with diabetes have problems with their feet, due to poor circulation and nerve damage. Wear comfortable and supportive running shoes.
- Be consistent - to reap the benefits of exercise for diabetes, it should be undertaken regularly.