1. Why Does Physical Activity Help Control Blood Glucose?

When the body engages in physical activity, muscles require energy to function. During this process, glucose from the bloodstream is taken up by muscle cells and used for energy, thereby lowering blood glucose levels. In particular, physical activity also improves insulin sensitivity, meaning that insulin works more effectively and helps glucose enter cells more easily.

For people with type 2 diabetes, this is an extremely important benefit because most patients experience insulin resistance. Simply maintaining regular physical activity can significantly improve fasting blood glucose, postprandial blood glucose and HbA1c levels.

In addition to controlling blood glucose, physical activity provides numerous overall health benefits:

• Promotes weight loss and reduces visceral fat.

• Lowers blood pressure.

• Reduces LDL ("bad") cholesterol and triglycerides.

• Increases HDL ("good") cholesterol.

• Improves blood circulation.

• Reduces the risk of cardiovascular disease and stroke.

• Reduces stress and improves sleep quality.

• Enhances endurance and work capacity.

• Helps slow the progression of diabetes-related complications.

Note: In older adults, physical activity also helps maintain muscle mass, prevent osteoporosis and reduce the risk of falls.

2. How Much Physical Activity Is Enough for People with Diabetes?

A common misconception is that exercise must be strenuous to be effective. In reality, consistency and suitability are the most important factors.

General recommendations for adults with diabetes include:

• Engage in at least 150 minutes of moderate-intensity physical activity per week.
• Spread physical activity across at least 3–5 days per week.
• Avoid sitting continuously for more than 30–60 minutes.

• Combine aerobic exercise with muscle-strengthening exercises.

3. Appropriate Exercise Intensity

Patients should prioritize moderate-intensity physical activity. Signs of this level of intensity include:

• A faster-than-normal heart rate.
• Faster breathing while still being able to hold a conversation.

• Feeling warmer and sweating slightly.

Suitable activities include brisk walking, slow-to-moderate cycling, swimming, dancing, gardening and climbing stairs at a moderate pace.

For beginners, exercising for just 10–15 minutes per session is sufficient initially, gradually increasing to 30–45 minutes per day.

4. The Best Types of Exercise for People with Diabetes

Aerobic Exercise

This is the most important group of exercises for improving blood glucose control and cardiovascular health.

Suitable activities include brisk walking, cycling, swimming, light rope skipping, aerobic workouts and water walking.

Walking is the simplest, safest and most effective form of exercise. Numerous studies have shown that walking for just 15–20 minutes after meals can significantly reduce postprandial blood glucose levels.

Muscle-Strengthening Exercises

Strength training helps increase muscle mass, and muscles serve as the body's "glucose storage reservoir." People with greater muscle mass can utilize glucose more efficiently.

Suitable exercises include lifting light weights, resistance band exercises, squats, push-ups and sit-to-stand exercises.

These exercises should be performed 2–3 times per week, with rest days between sessions to allow muscles to recover.

Flexibility and Balance Exercises

These are particularly important for older adults and include yoga, tai chi and stretching exercises.

These activities help reduce joint stiffness and muscle pain while lowering the risk of falls.

5. The Best Time to Exercise

Exercise timing has a considerable influence on the effectiveness of blood glucose control.

After Meals Is the Ideal Time

Engaging in light physical activity approximately 30–60 minutes after eating helps:

• Limit postprandial blood glucose spikes.

• Improve digestion.

• Reduce feelings of heaviness and discomfort.

Walking for just 10–20 minutes after a meal can produce noticeable benefits.

Avoid Exercising When:

• Blood glucose is excessively high (>250 mg/dL with ketonuria).
• Experiencing a fever or infection.
• Extremely hungry.
• Insulin has just been injected into a muscle area that will be heavily engaged during exercise.

• The body is excessively fatigued or dehydrated.

6. Risks Associated with Improper Exercise

Although physical activity offers substantial benefits, exercising incorrectly can cause several dangerous complications for people with diabetes.

Hypoglycemia

This is the most common risk, particularly among people using insulin or glucose-lowering medications. Common symptoms of hypoglycemia include trembling hands, excessive sweating, dizziness, intense hunger, rapid heartbeat, severe fatigue and confusion.

To prevent hypoglycemia, patients should:

• Avoid exercising on an excessively empty stomach.
• Carry candy or sugary drinks.

• Monitor blood glucose levels before and after exercise.

• Adjust medications according to their doctor's instructions.

Exercise-Induced Hyperglycemia

Many people believe that the more intense the exercise, the better. In reality, excessively high-intensity physical activity can stimulate the release of stress hormones, causing blood glucose levels to rise instead.

This is particularly dangerous when:

• Blood glucose levels are already elevated.

• Ketones are present in the blood or urine.

Foot Injuries

People with diabetes often develop peripheral neuropathy, which reduces pain sensation in the feet and makes them more susceptible to:

• Cuts and abrasions.

• Blisters.

• Foot ulcers.

Important precautions include:

• Wearing appropriate footwear.

• Inspecting the feet daily.

• Avoiding walking barefoot.

• Stopping exercise if pain or injury occurs.

Cardiovascular Events

Older adults and people with cardiovascular disease should exercise with particular caution. Overexertion may cause:

• Angina (chest pain).
• Cardiac arrhythmias.
• Shortness of breath.

• Sudden increases in blood pressure.

People at high cardiovascular risk should undergo a cardiovascular examination before beginning a moderate-to-vigorous intensity exercise program.

7. Principles of Safe Physical Activity for People with Diabetes

To ensure that exercise is both effective and safe, patients should remember the following principles:

Warm up properly: Spend 5–10 minutes warming up to help the body gradually adapt, minimize injuries and reduce cardiovascular risks.

Increase intensity gradually: Avoid overexertion from the outset. Exercise intensity should be increased gradually according to the body's ability to adapt.

Stay adequately hydrated: Dehydration can cause blood glucose levels to rise further.

Monitor blood glucose levels: This is particularly important for people using insulin or experiencing unstable blood glucose levels.

Maintain consistency: The benefits of physical activity are sustainable only when exercise is maintained over the long term. Exercising moderately but consistently is better than overexerting oneself and then giving up.

8. Tips for Maintaining Long-Term Physical Activity

Many people give up exercising after just a few weeks because they choose activities that are too difficult or unsuitable for their abilities. To maintain a sustainable exercise routine, patients should:

• Choose activities they enjoy.
• Exercise with friends or family.
• Set small, realistic goals.

• Track their progress each week.

• Incorporate physical activity into daily routines, such as taking the stairs, walking while talking on the phone or doing household chores.

Most importantly, physical activity should become part of a healthy lifestyle rather than a compulsory task.

Physical activity is an extremely effective "natural medicine" for managing diabetes. An appropriate exercise program can help lower blood glucose levels, improve insulin sensitivity, manage body weight and reduce the risk of cardiovascular complications. However, patients need to choose suitable forms of exercise, maintain regular physical activity and avoid overexertion or improper exercise techniques.

In diabetes management, nothing can replace a healthy lifestyle. By dedicating just 30 minutes each day to appropriate physical activity, patients can take a significant step toward better blood glucose control and long-term health protection.

Assoc. Prof Nguyen Trong Hung, PhD

Director, Center for Nutrition Counseling, Rehabilitation and Obesity Control, National Institute of Nutrition