Blood Sugar Management: Why Timing Your Exercise After Meals Matters

If you have diabetes, keeping your blood sugar within a healthy range is a constant task.

And if you like to hit the gym or hike the trails, you may wonder: Does exercise lower blood sugar? Any form of exercise can lower your blood sugar, but when you work out can impact how your blood sugar changes — especially after meals.

Registered dietitian and diabetes educator Emma Rueth, RDN, LDN, CDCES, explains the connection between exercise and eating.

Can exercise lower blood sugar?

Yes, exercise can lower your blood sugar in the moment and, with consistency, in the long term. During exercise, your muscles use sugar (glucose) from your blood as fuel. Exercising also helps your cells use insulin more efficiently — during exercise and over the course of the next several hours.

This is why the American Diabetes Association (ADA) recommends exercise five days a week. Consistent exercise increases insulin sensitivity, which helps decrease your blood sugar and hemoglobin A1C. Keeping blood sugar stable and in target can dramatically reduce your risk of heart disease and other complications of diabetes.

Best time to exercise for blood sugar control

While the ADA doesn’t provide specific recommendations for the timing of exercise, exercising soon after eating may help keep your blood sugar in a healthy range.

If you have Type 1 or Type 2 diabetes, the goal is to keep blood sugar at or below 180 mg/dl two hours after a meal. Research shows that glucose levels hit their peak within 90 minutes of a meal most of the time.

Rueth suggests checking your blood sugar before, during and after exercise to better understand your trends.

“This can help you determine whether you’re at a safe blood sugar level to start exercise, and how exercise impacts your blood sugar for the rest of the day,” she says. “Using a continuous glucose monitor (CGM) can help you track this.”

Types of exercise that help

The ADA recommends 150 minutes of moderate exercise — ideally broken into 30-minute workouts five days a week — or 75 minutes of rigorous exercise weekly. The ADA also recommends avoiding more than two days in a row with no structured physical activity.

If you have diabetes, certain exercises may help lower your blood glucose. Examples include:

• Walking
• Tai chi
• Yoga
• Dancing
• Swimming

But can exercise raise blood sugar?

“Especially for people with Type 1 diabetes, blood sugar may spike during short periods of high-intensity exercise,” says Rueth. “This is normal and, even with the possibility of a small increase in blood sugar, high-intensity exercise is still associated with better glucose stability.”

How to tell if it’s safe to exercise

It’s a good idea to check your blood sugar levels before, during and after physical activity. A continuous glucose monitor (CGM) can help with this.

Before exercise

Before you begin your workout, it’s important to check your blood glucose. A typical, healthy exercise range is 140 mg/dL to 160 mg/dL. If your level is too high — 300 or more — postpone exercise until your blood sugar is back in a healthy range. If you use an insulin pump, consider changing the setting to “exercise mode.”

During exercise

There’s a chance that your blood glucose levels could dip too low during a workout. Your healthcare provider may recommend checking your levels during exercise, especially if you take insulin or other medications that can cause hypoglycemia.

And if you plan on working out for more than 30 minutes or are trying out a new type of exercise, plan on checking your blood sugar more often.

It’s also important to pay attention to how you’re feeling. Stop physical activity if you feel:

• Weak
• Shaky
• Dizzy
• Confused

In those situations, your blood sugar may be too low. Rueth recommends that you bring a source of rapid-acting carbohydrates, like glucose tablets, whenever exercising. Other options that can raise your blood sugar levels quickly include fruit juice, soda or hard candy.

After exercise

Keep in mind that low blood glucose can occur during or long after physical activity. It’s more likely to occur if you:

• Take insulin or an insulin medication.
• Skip meals.
• Exercise for a long time.
• Exercise strenuously.

Having a post-workout snack can help prevent a drop in your blood sugar levels.

“A balanced snack that includes protein and carbs will also help your muscles recover,” Rueth says.

Take precautions with evening exercise

While it’s important that you know your blood sugar levels before activities, it’s particularly crucial to measure your blood sugar if you exercise in the evening.

“If you go to bed and your glucose drops below 70 mg/dL during the night, you may not feel the symptoms of hypoglycemia,” warns Rueth. “This can create a dangerous situation.”

Key takeaways

Exercising after a meal is a good way to reduce blood sugar levels and lower your risk of complications from diabetes, including heart disease. Using a CGM can help keep you aware and safe while introducing or increasing regular exercise.

“Before starting or changing your exercise regimen, talk with your doctor to determine what is best for you,” concludes Rueth. “If you’re on any medications that can cause hypoglycemia, it’s crucial you speak with your doctor first.”