Exercise-induced hypoglycemia (EIH) symptoms may include sweating, dizziness, and difficulty concentrating during or after physical activity. Fueling your body and adjusting insulin levels (if you have diabetes) may help prevent them.
Medically reviewed by Daniel Bubnis, M.S., NASM-CPT, NASE Level II-CSS
Medically reviewed by Daniel Bubnis, MS, NASM-CPT, NASE Level II-CSSon May 4, 2023
EIH occurs when your blood sugar level drops too low during or after exercise. This may be a one-off incident, or you may constantly experience symptoms.
This article will discuss what exercise-induced hypoglycemia is, its common symptoms, and how to prevent it.
Blood sugar is the primary energy source for your body. Usually, blood sugar levels are regulated by insulin, a hormone the pancreas produces.
Insulin helps move glucose from the bloodstream into the body’s cells, where it’s used for energy.
When your blood sugar is too low, your body may have trouble producing enough energy to perform bodily functions.
What is EIH?
EIH is a type of low blood sugar that occurs during or after physical activity.
During exercise, your body needs more sugar than usual for energy. According to a 2016 study, your muscles may use 50 times more glucose when you work out. To make this possible, your pancreas releases extra insulin, which increases the amount of sugar transported from your bloodstream into your cells.
Sometimes, your body may release too much insulin during exercise. Your body may react by trying to get rid of the insulin too quickly, which may cause EIH.
Similarly, exercising while already having low blood sugar levels may trigger EIH, even if the insulin release is not unusually high.
Symptoms of EIH
Symptoms of EIH may include:
sweating
trembling
lightheadedness
confusion or lack of concentration
fatigue
unusual irritation, frustration, or anger
intense hunger
rapid heartbeat
shortness of breath
weakness
headache
These symptoms may be similar to those of general hypoglycemia, but they occur specifically during or after physical activity.
Some people may experience EIH with no accompanying symptoms.
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medical conditions related to hormonal levels, organ failures, or cancerous growths
If you exercise while having any of these contributing factors, you may have a higher chance of experiencing EIH.
For example, running after fasting or joining a Zumba class when taking certain medications may contribute to your blood sugar dropping too low.
Who’s more likely to experience EIH?
Some people may be more likely to experience EIH. This includes people with type 1 or type 2 diabetes who take insulin or certain diabetes medications. It also includes people with impaired glucose tolerance, which means they have high blood sugar levels but have not received a diagnosis of diabetes.
That said, EIH can happen to anyone who performs moderate to intense physical activity.
Is EIH a sign of diabetes?
EIH isn’t necessarily a sign of diabetes, but it can be.
If you have diabetes and experience EIH, your diabetes management plan may need a review. If you have not received a diagnosis and have no other contributing factors but keep experiencing symptoms, it’s highly advisable that you let a doctor know about it.
Treatment for EIH
EIH is not harmful for most people, though it may be more serious for those with diabetes.
If you’re currently living with EIH, consuming fast-acting carbs — like glucose tablets, chocolate, or fruit juice — might help because they raise your blood sugar quickly. In addition, try to rest until you feel better, and hydrate by drinking plenty of liquids.
If you have diabetes and experience EIH, you may also need medical intervention. It’s important to follow your health team’s instructions. For instance, a healthcare professional may instruct you to administer insulin or other blood sugar management drugs and have you regularly monitor your blood sugar level.
Prevention of EIH
Consider these strategies to prevent EIH:
Eat a balanced meal or snack before exercising: This can help ensure your blood sugar level is high enough to fuel physical activity.
Pay attention to how you feel during exercise: If you experience any EIH symptoms, such as dizziness or trembling, it’s better to pause and rest. Consider refueling your body before your symptoms worsen.
If you have diabetes, these tips may further help you avoid EIH:
Regularly monitor your blood glucose level before, during, and after exercise: This can help you identify patterns and work with your doctor to make necessary changes to your treatment plan.
Adjust your insulin dosage before exercising: Your medical professional can help you determine the correct dosage based on your needs and EIH history.
Avoid physical activity for a while: In severe cases, your health team may recommend that you avoid physical activity until your blood sugar level is better managed.
When to see a doctor
If you have diabetes, working with your doctor to develop a plan for managing your blood sugar level at rest and during exercise is a good idea. This is especially important if you start experiencing EIH.
Similarly, consider consulting your doctor if you regularly experience possible EIH symptoms, even if you haven’t received a diabetes diagnosis. A health professional can help determine the underlying cause of your symptoms and develop an appropriate treatment plan.
If you’re experiencing EIH and your symptoms have not improved despite resting, hydrating, consuming carbohydrates, and taking diabetes medication (if you have diabetes), it’s a good idea to seek medical assistance.
Summary
EIH is when blood sugar drops too low during or after exercise.
Symptoms can include sweating, dizziness, confusion, and difficulty concentrating.
The best way to prevent or treat EIH is to:
monitor your blood glucose level before, during, and after exercise
adjust your insulin dosage if you have diabetes
eat a balanced meal or snack before exercising
carry a source of fast-acting carbohydrates with you during physical activity
If you regularly experience symptoms that may be related to EIH, consider speaking with your doctor to determine possible causes and develop an appropriate treatment plan.
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