How Exercise Affects Blood Sugar


Exercise is one of the best strategies that you can use to keep blood glucose levels in a lower, safer range. However, sometimes blood glucose readings can give you unexpected results during and after exercise. First, let’s look at how your body will naturally respond to exercise.

3 Sources of Blood Glucose

Your body needs glucose to survive. It is the fuel that each cell turns into energy for function. This blood glucose comes from three sources:

  • The food you eat.
  • Glycogen stored in muscle tissue. Your body stores this energy to make sure that your muscles will have enough energy to keep working when you need them.
  • Glycogen stored in the liver. This source of glucose is steadily and gently released while you sleep to help stabilize blood glucose levels while you sleep. It can also be released in an emergency to give you a burst of energy.

When you are working out, your body will go through four phases of glucose consumption to keep up with the rigors of physical activity.

  1. The body will burn the blood glucose first. This is glucose from the food that you have eaten. Insulin will shuttle this glucose into cells to be used as an immediate source of energy.
  2. As your muscles work, they begin to release stored glucagon which is converted into blood glucose and burned for energy to keep your muscles working. Your liver will also begin to release glucagon as it detects that blood glucose levels are diminishing.
  3. After about 30 minutes the body is running low enough on stored glucose that it will begin converting fat into energy. This is less efficient, so exercise becomes more difficult.
  4. Blood sugar levels will remain lower for anywhere from 4 to 24 hours as the body converts available glucose back into glucagon to be stored in muscle and liver tissue for future use.

When you exercise for an hour five days a week you help to use up excess glucose stores so that the blood glucose that you get from eating food can be used more efficiently. This process helps to reduce insulin resistance over time.

How Insulin Injections Affect Exercising Blood Glucose Levels

If you are using insulin injections, you must talk to your doctor about appropriate insulin use before exercise. This is because insulin supplementation causes the body to use glucose more efficiently which may result in a dangerously low dip in blood glucose during exercise.

  • Those who use insulin injections may find that the extra insulin causes the blood glucose level to dip too low during exercise.
  • Those who use insulin injections may need to consume more glucose before and during exercise to counteract the lowering effects of insulin injections.
  • Test glucose levels before, during, and after exercise. Any time glucose levels dip below 100 mg/dL they are dangerously low. Eat a small 15-carbohydrate snack or glucose tablet and wait 15 minutes before testing again to see if blood glucose has risen to a safe level.

Sulfonylurea medications can have the same effect on blood glucose, causing it to dip too low during exercise. Talk with your medical provider before beginning a new workout routine to get an adjustment to medications if necessary.

This is Why Blood Glucose Levels May Rise During Exercise

When you exercise your body begins to release stored glucose into the bloodstream to keep up with the extra metabolic demands from a sudden increase in physical activity.

When you have low insulin levels your body can not effectively use the sudden increase in glucose levels, so they remain circulating in the blood rather than being burned for energy.

  • Recently consumed food may have caused blood glucose levels to rise before beginning exercise. Without sufficient insulin to process the glucose, it will remain higher for longer.
  • Test glucose levels before, during, and after exercise. If it is over 250 mg/dL, then it is too high to work out safely. This high level of glucose may cause the liver to release ketones, creating a very dangerous condition called diabetic ketosis. Test for proteins using a ketone test strip and seek medical attention immediately if blood glucose levels remain high for a prolonged period.
  • During exercise, your body will release stores of glycogen from muscles and the liver. These are backup glucose supplies that should help you keep going in an emergency. However, if you do not have the insulin to deal with these supplemental releases, then you will have a spike in blood glucose.
  • The liver is somewhat notorious for releasing emergency amounts of glucose into the bloodstream when it detects stress. This stress can come from overnight fasting or sudden bursts of activity like exercise. The liver does not know the difference and will release emergency glucose stores causing a blood glucose spike.

Test blood glucose every 30-minutes during a workout. If you discover that blood sugar levels keep rising and remaining high during physical activity, then talk to your healthcare provider.

This is Why Blood Glucose Levels May Crash During Exercise

The condition where blood glucose levels dip dangerously low is called hypoglycemia. Even when you are struggling to manage diabetes you may have alternating periods where you experience hypoglycemia.

Hypoglycemia occurs when there is more insulin than necessary for processing the available blood glucose. This is more typical for those who are supplementing with insulin injections or sulfonylurea medications, but it can happen to anyone with an imbalance between blood glucose and insulin.

If your body has too much insulin and not enough blood glucose, then you can quickly run out of glucose when you start to exercise.

Your body must have blood glucose to keep you alive, so a sudden and prolonged crash in blood glucose can result in organ damage and even death if left untreated.

You need to know the signs of hypoglycemia:

If you are experiencing symptoms of hypoglycemia, you must treat it immediately. Consume a small snack such as a half cup of fruit juice or a glucose tablet to raise blood glucose levels quickly. This should be about a 15-carbohydrate portion. Wait for 15-minutes and then test blood glucose to see if additional carbohydrates are needed to raise blood glucose above 100 mg/dL.

Supplements Can Help Balance Glucose and Insulin Levels

The ideal condition is where your blood glucose is balanced with insulin levels. This provides your cells with the energy to maintain activity without causing dangerously low glucose levels. Aside from insulin injections and other prescription medications, there are some supplements that you can use to help achieve a more balanced state.

Several supplements have been researched thoroughly for their effectiveness in helping to lower blood glucose levels naturally such as inositol and DCI. Lowsitol is a once-daily supplement that combines 10 of these ingredients that are known to help the body metabolize glucose more efficiently and burn body fat.

Protein powders are widely used for post-workout recovery because they help to replenish nutrients that are metabolized during a vigorous workout without raising blood glucose levels. Balance is a whole-food supplementthat provides vitamins, amino acids, trace minerals, and protein to rebuild muscle and replenish glucagon stores without raising blood glucose levels.

Dehydration is a major culprit behind elevated blood glucose levels. When working out, hydration is key to maintaining cellular health and metabolic efficiency. Hydratedelivers antioxidants, electrolytes, and key vitamins and minerals to help your body get hydrated and balanced.

Key Takeaways

When you exercise and begin to burn blood glucose, your body will try to compensate for this by releasing additional glucose into the bloodstream.

If you have high levels of insulin, this glucose will get burned up and you will still not have enough blood glucose resulting in a hypoglycemic state requiring emergency glucose supplementation.

If you have low levels of insulin, these pulses of additional blood glucose will remain in the bloodstream for longer than is healthy for you and may require medical attention.

Blood glucose testing is the only way to preempt complications and should be done before, during, and after exercise so that intervention can be carried out before a dangerous complication occurs.

Natural supplements and early intervention can help to achieve optimal outcomes for both conditions.



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