Contributed by Dr Linsey Gani, Endocrinologist at LG Endocrinology.
Regular exercise can help people with diabetes manage their blood glucose while supporting cardiovascular and overall health. A 2025 analysis of 158 studies involving 17,059 people with type 2 diabetes found that exercise reduced HbA1c by an average of 0.40 to 0.61 percentage points, depending on the type of activity¹.
However, glucose levels can rise or fall during and after exercise, particularly for people using insulin or certain diabetes medications. The type and intensity of activity that is suitable for you may also depend on your current fitness and any diabetes-related complications.
This article explains how to exercise safely with diabetes through 13 practical tips. Keep reading to find out more!
What to Know Before Exercising
For people using insulin, recent doses and meals can affect how blood glucose responds to exercise. Aerobic activity helps the muscles use more glucose, so levels may fall quickly when more insulin is active.
Your response may not be the same every time, even when you repeat the same activity.
Factors that can affect your glucose levels include:
- Your starting glucose level and whether it is rising or falling
- Recent insulin doses and the timing of meals
- The type, intensity and duration of exercise
- Hydration, temperature and humidity
- Stress, illness or lack of sleep
- Exercise performed earlier in the day or on the previous day
If you use multiple daily insulin injections, an insulin pump or an automated insulin delivery system, work with your diabetes care team to develop a plan for different types of activity.
What to Do Before You Exercise
A little preparation can help you recognise potential risks and make the necessary adjustments before you start.
1. Check Whether the Exercise Is Suitable for You
You can usually begin with light activity and increase the duration and intensity gradually. However, speak with your doctor before starting a new exercise programme if you:
- Have been physically inactive for a prolonged period
- Plan to begin vigorous or high-intensity exercise
- Have heart or kidney disease, significant visual impairment or another diabetes-related complication
- Have peripheral neuropathy, reduced sensation in your feet or an active foot ulcer
- Experience frequent or severe hypoglycaemia
- Have difficulty recognising the symptoms of low blood glucose
- Experience large or unpredictable changes in your glucose readings
2. Plan Your Food and Insulin Around Exercise
The amount of carbohydrate or insulin adjustment you may need depends on when you last ate, how much insulin remains active and the type and duration of exercise planned. Aerobic activities often lower glucose, while sprinting, heavy resistance exercise and other high-intensity activities may cause a temporary rise.
Depending on their care plan, people using intensive insulin regimens may need to adjust their insulin or carbohydrate intake. Do not make substantial changes on your own. Your doctor can help you develop a strategy based on your usual glucose response.
3. Adjust Your Insulin Pump or Automated Insulin Delivery Settings
Some insulin pumps and automated insulin delivery systems have an exercise mode, activity setting or temporary higher glucose target. Depending on the device and the type of activity, this may need to be activated before exercise to reduce active insulin when you begin.
Avoid completely suspending insulin unless this forms part of your agreed plan. Insulin that has already been delivered can continue to act, while stopping delivery for too long may lead to high blood glucose or ketone production. As insulin pumps work differently, discuss the appropriate settings and timing with your doctor.
4. Get Your Exercise Essentials Ready
Before leaving home, prepare the items you may need during the session:
- Water
- Fast-acting carbohydrate
- Your glucose meter, CGM receiver or compatible phone
- Diabetes identification, where appropriate
- Emergency glucagon, if prescribed
- Supportive footwear and comfortable clothing
Keep your phone or another way to contact someone within reach. If you’re beginning a prolonged or unfamiliar activity, consider exercising with someone who knows how to recognise and respond to severe hypoglycaemia.
5. Know When to Postpone Exercise
Delay exercise if:
- Your blood glucose level is below 4.0 mmol/L
- You have untreated hypoglycaemia or your glucose is falling rapidly
- You feel unwell, feverish or dehydrated
- You are vomiting or cannot keep fluids down
- You have a new foot wound, ulcer or infection
- Your glucose is markedly elevated, and ketones are present
- Your diabetes care plan advises you not to exercise at your current glucose level
For people with type 1 diabetes or significant insulin deficiency, exercising when blood glucose is very high and ketones are present may raise glucose further and increase the risk of diabetic ketoacidosis. Follow your sick-day or high-glucose plan and seek medical advice when needed.
What to Do During Exercise
During exercise, pay attention to changes in both your glucose level and how you feel. Act early if something does not feel right.
6. Monitor Your Blood Glucose and Symptoms
If you take insulin or medication that may cause hypoglycaemia, you may need to check your glucose during prolonged, intense or unfamiliar activity. If your blood glucose level is below 4.0 mmol/L, postpone exercise and follow your care plan to raise it to a safe range. Wait until it has returned to a safe range and you feel well before resuming exercise.
CGM trend arrows can also help you see whether your level is stable, rising or falling, although a finger-prick test may be needed if the sensor reading does not match your symptoms.
People who do not use insulin or medication associated with hypoglycaemia generally have a lower risk of exercise-related low blood glucose and may not need to monitor during every session. Ask your doctor how often you should check based on your treatment and activity.
7. Keep Fast-Acting Carbohydrates Within Reach
If your treatment can cause hypoglycaemia, carry a rapidly absorbed source of carbohydrate whenever you exercise. Suitable options may include:
- Glucose tablets or gel
- Fruit juice
- A regular, non-diet soft drink
- A carbohydrate-containing sports drink
Keep it close enough to use immediately rather than in a locker or car. This also applies to light but prolonged activity, such as a long walk.
8. Exercise Safely in Singapore’s Heat and Humidity
Hot and humid conditions can increase sweating, dehydration and fatigue. Where possible, exercise during cooler parts of the day or choose an indoor, air-conditioned environment.
Drink fluids before, during and after activity, wear light, breathable clothing, and reduce your intensity when conditions are especially hot or humid. Stop and move somewhere cool if you feel faint, confused, nauseated or unusually weak.
9. Wear Suitable Footwear and Protect Your Feet
Diabetes-related foot problems can affect sensation or circulation, making small injuries harder to notice. Wear well-fitting, supportive shoes with moisture-wicking socks, and avoid exercising barefoot.
Check your feet before and after activity for blisters, cuts, redness, swelling or other changes. Stop if you develop new discomfort and seek medical advice if a wound does not heal promptly.
10. Know When to Slow Down or Stop
Stop exercising if you develop any of the following:
- Shakiness, sweating or unusual hunger
- Dizziness, weakness or blurred vision
- Confusion or difficulty concentrating
- A fast heartbeat or sudden loss of coordination
- Chest discomfort
- Severe shortness of breath
- A new foot injury
If you suspect hypoglycaemia, check your blood glucose and treat it according to your care plan. Seek prompt medical attention for chest discomfort, severe breathlessness or symptoms that do not improve.
What to Do After Exercise
Exercise can continue to affect your glucose after the activity ends. Monitoring your recovery helps you manage both delayed low blood glucose and temporary post-exercise rises.
11. Monitor for Delayed Hypoglycaemia
Low blood glucose can occur during exercise, immediately afterwards or several hours later, including overnight. This is because insulin sensitivity may remain increased while your muscles replenish their glucose stores.
Continue monitoring after prolonged or unfamiliar activity and check your glucose before bed when advised, particularly after afternoon or evening exercise. Review your CGM alerts if you use one and follow your plan for post-exercise meals or snacks. Speak with your doctor if you experience repeated or overnight hypoglycaemia.
12. Watch for High Blood Glucose After Exercise
Not every type of exercise lowers glucose. Sprinting, high-intensity intervals, competitive sport, and heavy resistance training may cause a temporary rise in blood glucose because stress hormones prompt the liver to release stored glucose. High readings can also result from insufficient insulin, extra carbohydrate or reducing insulin delivery too much.
A gentle cool-down may help moderate the rise for some people. Avoid taking an unplanned insulin correction immediately after intense exercise unless this is part of your care plan, as insulin sensitivity may still be increased and your glucose could fall later. If glucose remains high, you feel unwell, or ketones are present, follow your high-glucose plan and seek medical advice where appropriate.
13. Record How Your Body Responds
When you begin a new activity, keep a simple record of:
- The type and duration of activity
- Your meal and insulin timing
- Glucose readings before, during and after exercise
- Any carbohydrate consumed and your later glucose response
Over time, these notes can help you and your doctor identify patterns. This makes it easier to plan future sessions with greater confidence and fewer unexpected glucose changes.
Exercise Safely and Build Confidence Over Time
Glucose responses to exercise vary between people and activities. Begin gradually and use your readings to learn how your body responds. If you take insulin or a medication that can cause hypoglycaemia, follow the monitoring and adjustment plan provided by your doctor.
At LG Endocrinology, our endocrinologist can help you understand and manage how exercise affects your blood glucose. If you are unsure how to exercise safely with diabetes, book an appointment for advice based on your treatment and glucose response.
Disclaimer
This information is provided for general education. It does not replace personalised medical advice. Please consult your doctor for guidance on the medications that may be appropriate for you.
Dr Linsey Gani is an endocrinologist experienced in conditions related to hormonal imbalances, including those affecting fertility, menstrual health, and reproductive function. Dr Gani completed her residency in Melbourne, Australia. She is a fellow of the Royal Australian College of Physicians and the Academy of Medicine, Singapore.
Reference
¹Retrieved from Diabetes Research and Clinical Practice.
Images: Envato
Melissa Fann
