Exercise is a crucial part of managing diabetes. It can help you:

• Improve blood glucose level (BGL) control
• Boost overall fitness
• Manage weight
• Lower the risk of heart disease and stroke
• Enhance overall well-being
  

Diabetes and exercise can be tricky, especially when it comes to managing blood BGLs. Keep track of your BGLs before, during, and after exercise to see how your body reacts and avoid harmful fluctuations.

By understanding your body’s response and following these tips, you can enjoy the benefits of exercise while keeping your BGLs stable. Be sure to work with your healthcare team to create a personalised plan for exercise and blood glucose management.

Why do BGLs DROP during or after exercise?

During exercise, your muscles use glucose as fuel, and afterward, they need to replenish their stores. This process lowers your BGLs. Plus, your body becomes more sensitive to insulin during and after exercise, so you may need to decrease your insulin dose.

Why do BGLs GO UP during or after exercise?

High-intensity exercise or competitive sports can raise your BGLs due to stress hormones and your liver releasing extra glucose. Be cautious when correcting high BGLs, as they often drop right after or in the hours following exercise.

Monitor your BGL pattern before making corrections. If your BGL is above 15mmol/L (180mg/dL) before exercise, it may indicate insufficient insulin. Check for ketones – if they are above 0.6mmol/L, avoid exercising.

Before Exercise – Blood Glucose Checking & Planning

• Check BGLs. Measure your BGL 15-30 minutes before exercising. For people on insulin or Sulphonylureas (e.g. Gliclazide, Glipizide) it’s crucial to check beforehand.
  

Consult Your Diabetes Healthcare Professional about:

• How exercise may affect your BGLs
• The best time to exercise for your body and medication regimen
• Adjustments to medications or food before exercise

General Guidelines for BGLs Before Exercise:

• <4mmol/L (<70mg/dL) – This is hypoglycaemia (a hypo). Postpone exercise until you’ve handled the hypo and your BGL is back in a safe range.
• 4-5mmol/L (70-90mg/dL) – Consume a longer-acting carbohydrate (e.g. fruit or milk) before exercising. If food is not available, HYPO DUO Step 2 provides a convenient source of longer-acting carbohydrate.
• 5-10mmol/L (90-180mg/dL) – Ideal range for exercise.
• >10mmol/L (180mg/dL) – Exercise with caution, especially if BGLs stay above this level. Consider gentle exercise and consult your diabetes healthcare team for ongoing management
• >15mmol/L (270mg/dL) – Postpone intense exercise. High BGLs can worsen and cause dehydration and may lead to ketone production in type 1 diabetes

Extra carb food may be needed for exercise lasting >30 minutes. This is even more likely if the pre-exercise insulin has not been reduced. As a general guide consider:

• 1 x 15g (15g) carb serve for each hour of gentle exercise
• 2 x 15g (30g) carb serve for each hour of moderate exercise
• 3 x 15g (45g) carb serve for each hour of intense exercise

During Exercise – Maintaining BGLs

• Watch for Low BGL Symptoms. If you feel shaky, weak, dizzy, or confused, check your BGL.
• Check Every 30 Minutes. This is essential during long workouts or when trying new activities. Adjust based on your BGLs.
• If BGL Drops Below 3.9 mmol/L (70 mg/dL), follow the 15-15 rule:
  – Eat or drink 15g of fast-acting carb
  – Wait 15 minutes then recheck your BGL. Repeat if still low
  – Eat or drink 15g of long-acting carb

After Exercise – Post Exercise BGL Monitoring:

• Check BGLs Immediately After Exercise: BGLs can drop for up to 24 hours post-exercise. Check your levels immediately and monitor for 4-8 hours, as muscles refuel most around 6 hours after activity.
• After exercise: Consider a snack containing longer-acting carbohydrates (e.g. yoghurt, fruit, or HYPO DUO Step 2) to support ongoing carbohydrate intake.
• Be Aware of Hypos: If BGLs drop below 4mmol (70mg/dL), handle the hypo accordingly. See how to handle a hypo here.

Key Points on Exercise and BGLs

• Exercise Benefits: Increases insulin sensitivity, helps muscles absorb glucose, and lowers BGLs for up to 24 hours post-activity.
• Hypoglycaemia Risk: Those on insulin or insulin-stimulating medications (Sulphonylureas) are at risk for low BGLs. Adjust insulin doses or meals to prevent hypoglycaemia.
• Carry Hypo Treatment: Always have fast-acting carbs for handling a hypo and long-acting carbs to stabilise BGLs afterward. E.g. HYPO DUO Step 1 & Step 2.
• Supervise Children: Children with diabetes should be supervised by an adult who can assist in case of a low BGL.
• Change Injection Site: Avoid injecting insulin into arms, legs, or buttocks before exercise as it absorbs faster with muscle use. The abdomen is usually a better option.
• Exercise Over 30 Minutes: Exercise lasting 30 minutes or more may require adjustments to insulin or carb intake.
• More Carbs: Extra carbs might not be needed before exercise but may be necessary afterwards to prevent delayed hypoglycaemia.
• Change Alarms: Set your low CGM alarm higher (e.g., 5mmol/L or 90mg/dL) and consume HYPO DUO Step 2 or 15g of long-acting carbs to prevent exercise-induced hypo alarms.

Insulin dose changes

• For moderate or high-intensity, or longer-duration exercise, consider reducing your rapid-acting insulin dose and eating extra carbs to manage BGLs.
• To reduce the risk of overnight hypos, you may need to lower your long-acting insulin and/or have carbs before bed.
• Always consult your Diabetes Health Professional about insulin adjustments.