What Is Hypoglycemia?
Hypoglycemia is a condition caused by low blood glucose (blood sugar) levels. Glucose is the main way your body gets energy. The condition is most common in people with diabetes who have issues with medicine, food, or exercise. But sometimes people who don't have diabetes can also get low blood sugar. There are two kinds of nondiabetic hypoglycemia:
- Reactive hypoglycemia, which happens a few hours after you eat a meal
- Fasting hypoglycemia, which might be linked to medicine or a disease
Is hypoglycemia a sign of diabetes?
People with diabetes often have episodes of high or low blood sugar. In most cases, low blood sugar is caused by diabetes. But it can also affect people who don’t have diabetes.
Hypoglycemia vs. hyperglycemia
These two terms might sound similar, but they mean opposite things.
- “Hypo-” means low, so “hypoglycemia” is low blood sugar.
- “Hyper-” means high, so “hyperglycemia” is high blood sugar.
You can remember the difference by thinking of the word hyper, which means high energy.
Blood sugar is measured by how much glucose is in your blood. Everyone has a different “normal” level of glucose, but for most people, hypoglycemia is when your blood glucose drops below 70 milligrams per deciliter (mg/dL).
Severe hypoglycemia is when blood sugar goes below 54 mg/dL. This can make you faint. When your blood sugar is this low, you might need someone else to give you emergency treatment such as glucagon.
When you think of sugar, you might think of the sweet stuff in desserts. But there are a few different kinds of sugar, and not all of them are sweet. The kind that’s involved in blood sugar is called glucose. It’s found in sugary foods, bread, rice, and other carbohydrates.
Glucose is your body’s favorite source of energy. When you eat, your blood glucose goes up. Your blood delivers glucose to your cells. A hormone called insulin helps move glucose from the blood to your cells.
Later, when you run low on blood sugar, another hormone called glucagon tells your body to break down its backup supply of glucose. This backup supply, called glycogen, is stored in your liver and muscles. It’s turned back into glucose and released into your bloodstream. This helps keep your blood sugar stable until you eat again.
You can think of this whole process like a pizza delivery, where the “pizza” is glucose. Your bloodstream is like the highway that the delivery van uses to get to your house. Once the delivery van arrives, the pizza delivery person carries food from their van to your front door, just like insulin carries glucose from your blood to your cells. Back at the pizzeria, glucagon is like the manager. When fresh ingredients run low, glucagon tells the employees to take backup frozen pizza (glycogen) out of the freezer (liver). As soon as the frozen pizzas are reheated, or turned back into glucose, the staff loads them into the vans for delivery.
When this process goes smoothly, your blood sugar stays stable between meals. When something goes wrong, it can lead to hypoglycemia.
What causes low blood sugar without diabetes?
Usually, low blood sugar affects people with diabetes. But there are some reasons that you could have it without diabetes, including:
- Certain medications. Some medicines, such as the malaria drug quinine (Qualaquin), can cause low blood sugar. Other times, hypoglycemia happens when you take someone else’s diabetes medication by accident. Medications that can cause low blood sugar include pentamidine, beta-blockers, angiotensin-converting enzyme agents, and insulin-like growth factors.
- Some diseases. Severe hepatitis, cirrhosis, kidney failure, major infections, and heart disease can affect blood sugar. Sometimes, kidney problems make it harder for your body to pee out medicines. When you don’t pee them out, some medicines can collect and lower blood sugar.
- Malnutrition. Long-term starvation, such as when you have anorexia, can cause your body to use up its backup glycogen stores. This leads to hypoglycemia.
- Drinking too much alcohol. If you drink too much alcohol without eating, the liver can’t break down its backup glycogen supply into glucose. This causes low blood sugar.
- Some cancers. Certain pancreatic tumors can cause your body to make too much insulin. As a result, your body moves glucose out of the bloodstream faster than it can be replaced.
- Hormone issues. Some disorders, especially of the adrenal and pituitary glands, can affect hormones such as insulin and glucagon. Hypoglycemia also can happen when children don’t have enough human growth hormone.
What causes reactive hypoglycemia?
Reactive hypoglycemia is when you have low blood sugar within 2-4 hours after eating. Doctors don’t know exactly what causes it, but they think it happens when you have a sudden spike in blood sugar after eating simple carbohydrates (such as white rice, white bread, or cakes). This might trigger your body to make too much insulin, causing a rapid fall in blood sugar.
Other possible causes include:
- Having prediabetes or being more likely to have diabetes
- Stomach surgery (such as gastric bypass surgery)
- Rare enzyme defects
Usually, this type of low blood sugar gets better on its own. But to speed up the process, you can try eating more carbohydrates.
What causes fasting hypoglycemia?
This is a type of hypoglycemia caused by fasting (not eating for a long time). For most healthy people, fasting shouldn’t cause hypoglycemia. This is because your body knows how to manage blood sugar effectively, even when you haven’t eaten.
But sometimes, people without diabetes can get fasting hypoglycemia. This can happen when:
- Take certain medicines. Aspirin, beta-blockers, and sulfa antibiotics can affect your blood sugar.
- Regularly drink too much alcohol. Alcohol makes it hard for your body to store extra glucose in the form of glycogen. If you drink too much and don’t eat enough for several days, you might use up all your backup glycogen stores.
- Have certain illnesses. Diseases of the liver, kidney, heart, and pancreas can cause your body to use up more glucose than it can replenish with food or glycogen.
- Have low hormone levels. Hormones are important for managing your blood sugar. For example, cortisol raises your blood sugar. When you don’t have enough cortisol, you can get hypoglycemia.
- Have certain tumors. Some tumors affect your hormone levels. These tumors can be benign (noncancerous) or malignant (cancerous).
Causes for people with diabetes
When you have diabetes, your body has a hard time making or using insulin. Treatment usually includes insulin or other drugs to help manage your blood sugar. But if you take too much of these drugs or inject insulin into muscle instead of fatty tissue, then your blood sugar can drop.
In addition to insulin, medications called meglitinides and sulfonylureas can cause low blood sugar.
Repaglinide (Prandin) and nateglinide (Starlix) are two common meglitinides. Commonly used sulfonylureas include:
- Glimepiride (Amaryl)
- Glipizide (Glucotrol)
- Glyburide (Diabeta, Micronase)
- Micronized glyburide (Glynase)
Older types of sulfonylureas tend to cause low blood sugar more often than newer ones. Examples of older drugs include:
- Chlorpropamide (Diabinese)
- Repaglinide (Prandin)
- Tolazamide (Tolinase)
- Tolbutamide (Orinase)
You can also get low blood sugar if you drink alcohol or take allopurinol (Zyloprim), probenecid (Probalan), or warfarin (Coumadin) with diabetes medications.
You shouldn't get hypoglycemia if you take alpha-glucosidase inhibitors, biguanides (such as metformin), and thiazolidinediones alone, but it can happen when you take them with sulfonylureas or insulin.
If you have diabetes, ask your doctor if any of your medications are linked to hypoglycemia.
Your diet and activity levels are also important. If you don’t eat enough or exercise too much, but still take the same amount of medication, it creates an imbalance that lowers your blood sugar.
For instance, hypoglycemia can happen:
- When you wait too long to eat after an insulin injection
- After you eat a meal that has a lot of simple sugars
- If you miss a snack or don't eat a full meal
- If you eat later than usual
- If you drink alcohol without eating any food
- When you exercise more than usual
To avoid low blood sugar, don't skip meals if you have diabetes, particularly if you're taking diabetes medications. Balance your meals to include fiber, fat, and protein. A registered dietitian can help you find a meal plan that supports stable blood sugar.
If you have diabetes, it’s especially important to pay attention to your blood sugar when you’re sick. Some infections cause hormone changes that lead to high blood sugar. Others make it difficult to eat, which can make your blood sugar drop.
Ask your doctor in advance how to manage blood sugar when you get sick. For example, you might need to adjust your medications. If you are sick and keep throwing up, call your doctor. This could be a sign of a dangerous condition called ketoacidosis.
Hypoglycemia in pregnancy
Pregnancy causes hormone changes throughout your body. For example, during pregnancy you might make more estrogen, cortisol, and human placental lactogen. These are hormones that stop insulin from working. When this happens, it’s called insulin resistance. It causes your blood sugar to rise.
If you already have diabetes, pregnancy can make it worse. Even if you don’t have it, you can still develop a temporary form called gestational diabetes. When you have diabetes during pregnancy, you’re more likely to have episodes of hypoglycemia. This can harm you and your baby’s health.
Sometimes, your blood sugar can drop while you sleep. This can be caused by:
- High physical activity, especially near bedtime
- Drinking alcohol before bed
- Taking too much insulin
To avoid nocturnal hypoglycemia, have a snack before bed. This is especially important if you’re drinking alcohol.
Sometimes, low blood sugar can wake you up at night. But it doesn’t always, so using a continuous glucose monitor (CGM) can help alert you before it gets dangerously low.
Hypoglycemia Risk Factors
Some things can raise your risk for hypoglycemia. You’re more likely to have low blood sugar when:
- It’s hot and humid outside.
- Your schedule suddenly changes.
- You’re at a high altitude.
- You’re going through puberty.
- You have your period.
Hypoglycemia in newborns
To a certain extent, it’s normal for a baby’s blood sugar to drop soon after they’re born. This is because they’re used to receiving a steady flow of glucose through the placenta. After they are delivered, they no longer have this steady source of glucose. It takes them a little while to adjust to the change, and the hypoglycemia quickly gets better on its own.
But sometimes their blood sugar can drop too much. This can be caused by a variety of medical conditions. In particular, small and preterm newborns are at high risk for hypoglycemia because they have very little glycogen or fat stores. They also have relatively large brains that demand a lot of glucose for energy.
Hypoglycemia also affects newborns whose mothers had uncontrolled diabetes during pregnancy. When the baby is still developing, the mother passes extra glucose to the fetus through the placenta. As a result, the fetus regulates its blood sugar by making extra insulin (insulin doesn’t travel through the placenta). After the baby is born, they still have a lot of insulin in their blood. But they don’t have any more glucose being delivered through the placenta. As a result, the high insulin levels cause the baby’s blood sugar to drop. This usually happens within the first few hours after birth. It’s treated with intravenous (IV) glucose.
Most people feel low blood sugar symptoms of hypoglycemia when their blood sugar is 70 milligrams per deciliter (mg/dL) or lower. The symptoms may be different, depending on how low your blood sugar goes. They usually include:
- Pale skin
- Fast or irregular heartbeat
- Tingling or numbness, especially in your cheeks, lips, and tongue
- Extreme hunger
Nocturnal hypoglycemia has similar symptoms, but it can also cause:
- Difficulty sleeping
- Calling out in your sleep
As hypoglycemia gets worse, symptoms might include:
- Strange behavior
- Blurred vision
- Difficulty walking
- Passing out
If you think you have low blood sugar, it’s important to address it right away. Try having a high-sugar food or drink. But if you are having severe symptoms, call 911.
Sometimes, hypoglycemia doesn’t cause any symptoms. This happens when you have too many episodes of low blood sugar. Over time, your body gets used to these episodes and stops sending out its usual alarm signals, such as hunger or shakiness. As a result, you might not notice when your blood sugar gets low. This raises your risk for severe hypoglycemia and its life-threatening complications.
It is more likely to happen to people who:
- Have had diabetes for over 5-10 years
- Have frequent episodes of low blood sugar
- Take certain medications, including beta-blockers
If you get frequent bouts of hypoglycemia, your doctor might adjust your treatment or suggest training on how to recognize low blood sugar.
There are other ways to keep an eye on your blood sugar. These include:
- Manual blood sugar checks. Frequent checks can help you monitor your glucose. To do this, you prick your finger and test the blood with a blood glucose monitor.
- A continuous blood glucose monitor (CGM). This is a small device with a wire that’s inserted under your skin. A CGM tracks your blood glucose and alerts you when it gets low.
- A diabetes alert dog. Service dogs trained in diabetes care can signal when you have low blood sugar.
To diagnose nondiabetic hypoglycemia, your doctor will do a physical exam and ask questions about any medicines you take. They’ll want to know all about your health and any history of diseases or stomach surgery.
There’s more than one way to test for hypoglycemia. Usually, your doctor will check your blood glucose level, especially when you are having symptoms. To do this, they might prick your finger to collect a tiny blood sample, then test that sample in a small device called a blood glucose monitor. They’ll also check to see if you feel better when your sugar goes back to a normal level after you’ve eaten.
If your doctor suspects hypoglycemia but you feel fine at your appointment, they might ask you to fast until you start to have symptoms. In some cases, this fast could be overnight or even done over 3 days in a hospital. They’ll test your blood glucose level at different times throughout the fast. They also might order additional tests to look for tumors and other potential causes of hypoglycemia.
To check for reactive hypoglycemia, you may have to take a test called a mixed-meal tolerance test (MMTT). For this, you take a special drink that raises your blood glucose. The doctor will check your blood glucose levels over the next few hours.
To diagnose hypoglycemia, doctors use a formula called Whipple’s triad. This means that you must meet three conditions:
- You have symptoms of low blood sugar.
- These symptoms happen when you have low blood glucose (as measured by a laboratory test, not just a glucose meter or CGM).
- The symptoms disappear when your blood sugar goes back to normal.
If you meet all of these conditions, you have hypoglycemia.
Conditions That Mimic Hypoglycemia
Some diseases look like hypoglycemia but don’t cause low blood sugar. These include:
- Postprandial syndrome
- Heart problems, such as arrhythmia and valvular disease
- Psychiatric illnesses
Hypoglycemia has two forms of treatment: immediate and long-term. To protect your health, you need both.
When you start feeling the symptoms of hypoglycemia:
If you have diabetes, check your blood sugar. If it’s below 70 mg/dL (or the goal set by your doctor), eat or drink 15-20 grams of fast-acting carbohydrates. This might look like:
- A small piece of fruit, such as half a banana
- 1/2 cup of juice or regular (not diet) soda
- 1 tablespoon of honey, syrup, or sugar
- Hard candy, jelly beans, or gumdrops
- 3-4 glucose tablets (or as indicated by instructions)
- 1 tube of glucose gel (or as indicated by instructions)
Avoid snacks that contain a lot of fat (such as chocolate) or fiber (such as beans) because these slow down sugar absorption. Don’t be tempted to eat too many carbs, as this could accidentally cause your blood sugar to spike. Young children usually need less food to bring their blood glucose back to normal.
Check your blood sugar again in 15 minutes. If it’s still low, have another helping of these fast-acting carbohydrates. Keep doing these steps until your blood sugar is back to normal. Call 911 if you don’t feel well or if you can’t get your blood sugar back up.
- Even if you don’t have diabetes, eating a sugary snack like the ones described above can help bring your blood sugar back to normal.
In the case of severe hypoglycemia (blood sugar less than 54 mg/dL), you may need emergency glucagon treatment or intravenous glucose. Glucagon is a hormone that tells your body to make glucose by breaking down its backup glycogen supply. You can take it as a nasal powder (dry nasal spray) or shot in the butt, arm, or thigh.
If you have diabetes and take insulin, you should always keep a glucagon kit with you. You can get this kit with a prescription from your doctor. Show your family and friends where you keep it and how to use it in case of emergency.
After giving someone else a glucagon treatment, you should roll them over on their side. That way, if they vomit, they don’t choke. Then, call 911 for emergency help. If the person has passed out, they should wake up within 15 minutes of receiving the glucagon. If they don’t wake up during that time, give them another injection or nasal spray. Once they are awake and can safely swallow, give them a fast-acting carbohydrate (such as juice) and a long-acting carbohydrate (such as a sandwich).
After an episode of hypoglycemia, keep a close eye on your blood sugar for the next 2-3 days. If you have another episode during this time, its symptoms might be less noticeable.
You also need to treat the underlying cause of low blood sugar. If you have diabetes, talk with your doctor about how to best manage it. If you don’t have diabetes, make an appointment with your doctor to identify its cause.
Long-term treatment of hypoglycemia depends on what's causing it. For example:
- If a medicine triggers your low blood sugar, you may need to change the medication or adjust its dose.
- If a tumor is to blame, you may need surgery.
- If diet plays a role, nutritional counseling can help you manage your sugar intake.
Severely low blood sugar is treated with an immediate emergency dose of glucagon. The FDA has approved the following medications that contain glucagon or similar substances:
- Baqsimi, taken as a nasal powder
- Dasiglucagon (Zegalogue), taken by injection
- GlucaGen HypoKit, taken by injection
- Glucagon Emergency Kit, taken by injection
- Gvoke HypoPen, taken through injection
If you have diabetes and get hypoglycemia often, you might be tempted to take less insulin. But it’s important that you don’t change your medications without talking to your doctor first. Taking too little medication can make your diabetes worse.
Hypoglycemia can lead to:
- Falls and injuries
- Car accidents
- Higher risk for dementia
In severe cases, untreated hypoglycemia can cause:
- Organ failure
- Heart arrhythmias
- Brain damage
Call your doctor right away if:
- You are having symptoms of low blood sugar but don’t have diabetes.
- You have diabetes, and your low blood sugar doesn’t improve after having sugary foods or glucose tablets.
Fainting from hypoglycemia
Hypoglycemia may make you pass out. If so, you'll need someone to give you a glucagon shot.
Glucagon is a prescription medicine that raises blood sugar. You may need it if you have severe hypoglycemia. It's important that your family members and friends know how to give the shot if you have a reaction to low blood sugar.
If you see someone having a severe hypoglycemic reaction, call 911 or take them to the nearest hospital for treatment. Don’t try to give an unconscious person food, fluids, or insulin, as they may choke.
Living With Hypoglycemia
If you have frequent episodes of low blood sugar, get a medical alert bracelet. This can indicate how people should help you during an emergency.
Other tips include:
- Keep fast-acting carbohydrates on hand. Easy-to-carry snacks such as hard candies, fruit juice, and glucose tablets can quickly boost your blood sugar.
- Talk with your friends and family about hypoglycemia. Teach them how they can help you in an emergency.
- Get a glucagon kit. You might need to ask your doctor for a prescription. Always carry the kit with you, and teach your loved ones how to use it.
- Limit alcohol. If you enjoy a drink, have it with food. This way, it won’t cause a sudden drop in blood sugar.
- Enjoy a well-balanced diet. Talk with a dietitian about a meal plan that will keep your blood sugar steady.
- Exercise safely. Physical activity is an important part of your health. Talk with your doctor about finding an exercise plan that’s right for you. Ask about how to prevent or manage blood sugar dips after exercise.
Driving with hypoglycemia
Driving with low blood sugar is dangerous. If you're driving and you have hypoglycemia symptoms, pull off the road, check your blood sugar, and eat a sugary snack. Wait at least 15 minutes, check your blood sugar, and repeat these steps if needed. Eat a protein and carbohydrate source (such as peanut butter crackers or cheese and crackers) before you drive. Be prepared. Keep a sugar source, such as glucose tablets, in your car at all times for emergencies.
A balanced diet is essential for good health, and it only becomes more important when you have low blood sugar. Remember, there’s no such thing as a “perfect” or “one-size-fits-all” diet because each body is different. But here are some general tips:
- Avoid foods with refined sugar. Foods such as white bread and pasta cause blood sugar to spike.
- Eat plenty of fruits and vegetables. These contain important vitamins and nutrients.
- Add some soluble fiber to your diet. You can find soluble fiber in foods such as flaxseed and oat bran. They slow down sugar absorption and help regulate blood glucose.
Talk with a doctor or dietitian about finding a meal plan that’s right for you.
If you have diabetes, you can make some more easy changes to help keep your blood sugar steady:
- Eat at least three evenly spaced meals each day with between-meal snacks as prescribed.
- Exercise 30 minutes to 1 hour after meals. Check your sugars before and after exercise, and discuss with your doctor what types of changes you can make.
- Double-check your insulin and dose of diabetes medicine before taking it.
- If you drink alcohol, be moderate and monitor your blood sugar levels.
- Know when your medicine is at its peak level.
- Test your blood sugar as directed by your doctor.
- Carry an identification bracelet that says you have diabetes.
- Take care of yourself when you're sick, especially when vomiting.
- Carry a sugary snack with you everywhere.
- Inform your friends, colleagues, and family members that you're diabetic.
- Take all your medications exactly as prescribed.
If you don’t have diabetes, ask your doctor if you need to adjust what you eat or how much you exercise. Some diet changes might help:
- Eat small meals and snacks every few hours.
- Include a broad variety of foods, including protein, fatty, and high-fiber foods.
- Don't eat a lot of high-sugar foods.
Work with your doctor to figure out anything else that may be causing your symptoms.
Episodes of hypoglycemia, or low blood sugar, are common for people with diabetes. But they can be caused by other things as well. If you get shaky when you’re hungry or have other symptoms of hypoglycemia, talk to your doctor. They can help you figure out what’s causing your low blood sugar and make a plan to manage it.
How can I fix hypoglycemia quickly?
Eat a sugary snack, such as some jelly beans or 1/2 cup of juice or regular soda. Check your blood sugar again in 15 minutes. If it’s still low or you still don’t feel well, repeat these steps.
Can you be hypoglycemic and not diabetic?
Hypoglycemia is usually a sign of diabetes, but not always. When you don’t have diabetes, hypoglycemia can be caused by certain health issues and medications, drinking too much alcohol, or malnutrition.