Medically Reviewed By William C. Lloyd III, MD, FACS
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What is hypoglycemia?

Hypoglycemia occurs when an individual’s blood glucose—or blood sugar—level is lower than normal. Episodes of hypoglycemia can be a life-threatening emergency. Glucose is the main energy source that powers the body’s cells. Glucose levels vary throughout the day. Blood sugar rises and falls in response to eating, exercise, and other factors. In general, hypoglycemia is a blood sugar level less than 70 mg/dL. If you have diabetes, your care team will give you specific blood sugar level goals. So, your low blood sugar number may be different from someone without diabetes..

The most common cause of hypoglycemia is a side effect of diabetes treatment. In diabetes, blood sugar levels are too high. Many drugs that treat diabetes, including insulin, work by decreasing blood sugar levels. The goal is to keep blood sugar levels within a normal range. Sometimes, blood sugar levels go too low, resulting in hypoglycemia. Hypoglycemia is uncommon in people without diabetes.

For people with diabetes, maintaining a normal blood glucose range is a balancing act between medicines, carbohydrate intake, and activity. There are several factors that can increase the risk of hypoglycemia in people with diabetes. This includes not eating enough carbohydrates, skipping meals, and being sick. Low blood sugar can also occur if you increase your activity without adjusting the energy you take in.

Each person can experience low blood sugar differently. Commonly, hypoglycemia causes anxiety, hunger, irritability, shakiness and sweating. But there are a wide variety of hypoglycemia symptoms. So, it is important to learn your individual warning signs.

People with diabetes learn to test their blood sugar levels. This is the only way to know for sure if blood glucose is too low. Hypoglycemia treatment involves quickly increasing your blood sugar levels. You can accomplish this with high-sugar drinks, foods, candy, or glucose tablets. When people get severe hypoglycemia, a shot of glucagon may be necessary. If you have a glucagon emergency kit (by prescription), it is important for friends, family members, and co-workers to know how to give the glucagon shot in case you are unable to help yourself.

See your doctor if you have recurrent hypoglycemia. It may be a sign that your medications need adjustment. Recurrent low blood sugar levels can lead to hypoglycemia unawareness. This dangerous complication puts you at risk of life-threatening hypoglycemia episodes.

Seek immediate medical care (call 911) if someone with diabetes lost consciousness or their low blood sugar symptoms are not responding to treatment. Immediate medical care is also necessary if someone without diabetes has symptoms of low blood sugar.

What are the symptoms of hypoglycemia?

Hypoglycemia symptoms can vary from person to person. In general, they tend to happen very quickly, but some people may feel them coming on slowly.

Common symptoms of hypoglycemia

Common symptoms of low blood sugar include:

Serious symptoms that might indicate a life-threatening condition

Hypoglycemia can become serious and life-threatening. Seek immediate medical care (call 911) if you, or someone you are with, have any of these life-threatening symptoms including:

  • Abnormal behavior or inability to complete simple tasks
  • Inability to eat or drink

Emergency help is also necessary if low blood sugar symptoms do not respond to treatment or if the person does not have diabetes.

What causes hypoglycemia?

Hypoglycemia most commonly occurs as a side effect of diabetes medications. People with diabetes either do not have enough insulin or their body is resistant to it. Insulin is the hormone cells need to use glucose. Without it, glucose builds up in the blood. Insulin injections and other drugs can bring these levels back to normal by helping cells take up and use glucose. However, too much insulin or medication can result in hypoglycemia. It can also occur if you take diabetes medicines and do not eat enough or if you are more active than normal and do not adjust your food intake.

Hypoglycemia can occur, but is not common, in people without diabetes. Possible causes include:

  • Excessive alcohol use
  • Glycogen storage disease, which affects how the body uses stored glucose
  • Non-diabetes medications, such as pentamidine and quinine
  • Pituitary or adrenal gland problems

What are the risk factors for hypoglycemia?

If you have diabetes, several factors can increase the risk of developing hypoglycemia including:

  • Being sick
  • Drinking too much alcohol, especially without eating food
  • Increasing physical activity above normal without balancing your medicine or carbohydrate intake
  • Not eating enough carbohydrates to balance your insulin or medicine
  • Skipping or delaying a meal

How do you prevent hypoglycemia?

If you have diabetes, there are steps you can take to reduce the risk of hypoglycemia including:

  • Checking your blood sugar as directed or using a CGM (continuous glucose monitor)
  • Eating food if you decide to drink alcohol
  • Getting regular physical activity and learning how to do so safely by adjusting carbohydrates and medication
  • Sticking to a regular meal and snack schedule with the correct amount of carbohydrates

Your diabetes care team is there to help you understand how to manage your diabetes. Tell your team if you have recurrent hypoglycemia. They can guide you in balancing your carbohydrates, physical activity, and medications.

What are the diet and nutrition tips for hypoglycemia?

A hypoglycemic diet is simply a healthy, balanced diet. This includes lean meats, low-fat dairy, whole grains, and fresh fruits and vegetables. In general, people with diabetes should eat complex carbohydrates and limit simple carbohydrates and sugary foods. Sweets are fine to have on occasion, but you must balance them in your eating and exercise plan.

One of the key diet strategies for people with diabetes is learning how much of different foods you can eat. There are basically no foods that are off limits, as long as you understand how much you can have. For people who use insulin to treat diabetes, this is even more important. Carbohydrate counting is one of the main ways to keep track of your intake. A registered dietitian or diabetes educator is best able to help you understand how to plan your meals and handle last minute changes to your plan.

How do doctors diagnose hypoglycemia?

If you have diabetes, your doctor will talk with you about your blood glucose level goals. Your doctor will also let you know how often to check your blood sugar or whether you need a CGM. Checking or seeing your blood sugar levels is the only way to know for sure if your glucose level is too low.

In people without diabetes, doctors need to use a blood test to check blood glucose levels. This could be a quick point of care test in the office or emergency room or a blood draw from a vein for a lab test.

Your doctor may also ask you several questions related to your low blood sugar symptoms including:

  • What symptoms are you having?
  • When did these symptoms start?
  • When do your symptoms occur?
  • What, if anything, seems to trigger your symptoms or make them better?
  • What medical conditions do you have?
  • What medications do you take?
  • What is a typical diet for you?
  • How often do you eat?
  • What do you do for exercise? Have you changed your routine recently?

How is hypoglycemia treated?

People with diabetes need to know how to recognize and treat hypoglycemia. The ADA (American Diabetes Association) recommends a simple rule: 15 and 15. You need 15 grams of glucose and 15 minutes to see if it raises your glucose to at least 70 mg/dL. If your level is still low after 15 minutes, repeat the 15 grams of glucose.

Glucose tablets or gels are designed for rapid absorption. They also come in doses that let you measure 15 grams. Most foods and hard candies can take too long to absorb. If you do not have glucose tablets or gels, try the following:

  • Half cup (4 oz) of regular soft drinks or fruit juices
  • One tablespoon of honey, corn syrup, or sugar

It is tempting to consume large amounts of glucose quickly, but this can be counterproductive. A large sugar load can cause blood glucose levels to spike too high, which can also be dangerous. Once your blood sugar level is back up to at least 70 mg/dL, eat a meal or a snack. It can help stabilize your glucose levels.

Ask your doctor for recommendations specific for you. Your needs may be different. For example, your doctor may want you to use 30 grams instead of 15 grams. Or, your low glucose threshold may be different than 70 mg/dL.

For severe hypoglycemia, blood sugar levels are too low to use the 15 and 15 rule. Severe episodes occur when you need help to recover. Glucagon is necessary in these situations. Glucagon is a hormone with the opposite effects from insulin. It stimulates your body to release stored glucose. So, it can work when you are not capable of eating or drinking.

Glucagon comes as an injection or as a powder for nasal administration. It is important for friends, family members, teachers and co-workers to understand how to use your glucagon kit to help in case of emergency. You should see a doctor after an episode requiring glucagon.

What are the potential complications of hypoglycemia?

Hypoglycemia can lead to serious complications including:

  • Death
  • Hypoglycemia unawareness, which happens after repeated episodes. With time, the body becomes used to how it feels to have low blood sugar and the symptoms do not register anymore. This increases the risk of severe, life-threatening episodes.
  • Undertreated diabetes, which happens when fear of hypoglycemia leads people to use less insulin. While this may avoid low blood sugar, it can lead to uncontrolled diabetes. The complications of chronically high blood sugar levels include heart disease, stroke, kidney damage, neuropathy, and vision loss.

Hypoglycemia can also contribute to other complications by increasing the risk of falls, injuries, and car accidents. It increases the risk of dementia in older adults, as well. Do not ignore recurrent problems with hypoglycemia. Work with your doctor to rebalance your treatment plan and avoid future complications.

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Medical Reviewer: William C. Lloyd III, MD, FACS
Last Review Date: 2021 May 5
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THIS TOOL DOES NOT PROVIDE MEDICAL ADVICE. It is intended for informational purposes only. It is not a substitute for professional medical advice, diagnosis or treatment. Never ignore professional medical advice in seeking treatment because of something you have read on the site. If you think you may have a medical emergency, immediately call your doctor or dial 911.
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