Can exercise cause my blood sugar levels to drop?

Question: I love to exercise but I'm worried it can cause my blood sugar levels to drop hours later. Is that possible?

Answer: Managing diabetes, whether it is type 1 or type 2, means keeping blood sugar levels, within a specific range set by a medical provider. Blood glucose levels that are too high or too low can lead to serious health problems, so constant testing is required. Exercise is an important piece of in controlling my patient's blood sugars and improves their general well-being altogether. Exercise helps lower blood sugar levels in two ways.

  1. Regular exercise can help to shed unwanted pounds, which in itself can bring blood sugar levels down.
  2. Exercise at the right level can make your pancreas produce more insulin; thereby, lowering your blood sugars.

However, the degree to which the blood sugar is lowered can be very unpredictable.

Our body needs enough fuel for exercising and our body's main source of fuel is sugar. If you exercise hard enough and you don't eat the right kind of food before you work out, your sugars can drop very quickly. Depending on each individual, hypoglycemia can occur when their blood sugars hit a certain level. Some of my patients can get hypoglycemic if their sugars fall below 80 mg/dL, but mostly if they drop below 60 mg/dL.

In addition, blood sugar levels can still decrease hours after stopping exercise. To prevent complications, I have my patients test their blood sugars at least 30 minutes before and 30 minutes after exercise so they can see how their body responds. If their reading is under 100 mg/dL, I have them eat more of a carbohydrate-based snack and do not start exercising until the level is above 100 mg/dL. Then, I have them test again 30 minutes after their exercise, then test every 30 minutes for several hours after stopping. If their levels are low, they have to enough food or glucose tablets to make sure it stays at a safe range, especially before they go to bed. The American Diabetes Association recommends all patients with diabetes aim for at least 30 minutes of moderate-paced activity on at least five days per week. Those who need to lose weight might need more.

About Catherine Estipona

Catherine Estipona, MSN APN provides family-centered care as a Family Nurse Practitioner. In addition to her day-to-day care of patients, she serves as a Diabetic Educator in the state of Nevada for Lilly USA, LLC, a pharmaceutical company.

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