What Is Hypoglycemia?

Hypoglycemia occurs when your blood sugar (glucose) levels fall below what is considered normal. It is also called low blood sugar. The condition can be related to diabetes treatment, but it can also have other causes.

Glucose is the primary energy source for your body. When your blood glucose levels are too low, you may experience symptoms like shakiness, a fast heartbeat, anxiety, and hunger. If your blood sugar gets dangerously low, you may have symptoms like confusion, vision difficulties, behavioral changes, seizures, or even loss of consciousness.

Hypoglycemia is common in people with diabetes, though it tends to occur more often in people with type 1 diabetes. The true incidence is not known because mild hypoglycemia often goes unnoticed. 

This article explores the symptoms, causes, and complications of hypoglycemia. It will also help you understand when you should see a healthcare provider for hypoglycemia.

common hypoglycemia symptoms

Verywell / Laura Porter

Understanding Blood Sugar (Glucose)

Glucose comes from the foods we eat and serves as a source of energy for the body. Your body uses a hormone called insulin to move glucose into your cells where it can be used. When you have diabetes, your body doesn't make enough insulin, so the glucose remains in your blood.

Your body breaks carbohydrates down into sugars. When you have diabetes, these sugars can build up in your blood, leading to hyperglycemia or high blood sugar.

Taking insulin can help prevent high blood pressure, but it can also cause your blood sugar to become too low. Low blood sugar can also occur when you skip meals, eat too little, or exercise without changing how much you eat or adjusting your medication.

How to Treat Hypoglycemia

Hypoglycemia is an emergency. If your blood sugar levels fall below 70mg/dL, follow the 15-15 rule:

Immediately eat something that contains 15 grams of carbohydrate. Check your blood sugar 15 minutes later. If it's still low, repeat: Eat another 15 grams of carbohydrate and check your blood sugar 15 minutes later. Keep doing this until your blood sugar returns to normal.

Examples of foods that contain 15 grams of carbohydrate include:

  • 1/3 cup of granola
  • 15 large red or green grapes
  • 1 small apple
  • 1/2 cup ice cream or frozen yogurt
  • 2 small cookies
  • 1/2 cup fruit juice or non-diet soda

Hypoglycemia Symptoms

Hypoglycemia symptoms may occur when your blood glucose is 70 milligrams per deciliter (mg/dL) or below. The symptoms tend to follow a pattern that you'll probably very quickly learn to recognize if you have diabetes.

Frequent Symptoms

Common symptoms include:

  • Shakiness
  • Hunger
  • Fast heartbeat
  • Anxiety or panic
  • Tingling feeling around your mouth
  • Sweating
  • Headache
  • Tiredness
  • Inability to concentrate
  • Dilated pupils
  • Irritability
  • Restlessness
  • Nausea
  • Dizziness
  • Weakness
  • Loss of muscle control

Severe Symptoms

When your blood sugar becomes dangerously low—less than 54 mg/dL, as defined by the American Diabetes Association (ADA), which regards this parameter as severe or "level 2" hypoglycemia—you may have any of these symptoms as well:

Nocturnal Symptoms

During the night, you may have hypoglycemic episodes and not be aware of them. This is especially common with type 1 diabetes and a bit less common with type 2 diabetes.

Your body produces two hormones, glucagon and epinephrine, that help keep your blood sugar at normal levels. During sleep, glucagon production decreases. Added to this, type 1 diabetes tends to disrupt glucagon production and glucagon decreases with every episode as well.

Symptoms of nocturnal hypoglycemia include:

  • Night sweats
  • Nightmares
  • Talking or shouting in your sleep
  • Restlessness
  • Headache
  • Not feeling well-rested when you wake up
  • A glucose level that's higher than normal in the morning

To help prevent nocturnal hypoglycemic episodes, try eating a bedtime snack that's high in complex carbohydrates such as granola, oatmeal, or dried fruit. Keep your eating plan, exercise routine, and medication consistent in the afternoon and evening as well.

Also, be careful not to overdose on your insulin in the evening, which can lead to hypoglycemia.

Get Medical Attention

If you notice symptoms of nocturnal hypoglycemia, talk to your healthcare provider. Untreated, it can lead to life-threatening symptoms such as neurological consequences, like seizures and brain damage.

Hypoglycemia Unawareness

When you have diabetes and you have repeated episodes of hypoglycemia, your brain can become less able to recognize that you're hypoglycemic because your body stops showing symptoms. This is known as hypoglycemic unawareness and it often happens at night while you're sleeping.

It's more common in type 1 diabetes than in type 2. Your blood sugar levels can become dangerously low if this continues, leading to a coma or even death.

If you have chronic episodes of hypoglycemia, be sure to talk to your healthcare provider right away so you can get it under control.

What Causes Hypoglycemia?

Hypoglycemia has numerous causes, which are different depending on whether you have type 1 diabetes, type 2 diabetes, or don't have diabetes.

Type 1 Diabetes

Hypoglycemia is common in type 1 diabetes. It usually happens when you take more insulin than your body needs to process your food, but other things can cause it, too, including:

  • Not timing your insulin dose correctly around meals
  • Not monitoring your blood sugar closely when exercising or drinking alcohol
  • Hot, humid weather
  • Changes in your schedule, such as when traveling
  • Being at a high altitude
  • Puberty
  • Menstrual periods

Because you can't control some of those factors, it's especially important to pay attention to the ones you can control.

Type 2 Diabetes

Hypoglycemia is less common in type 2 diabetes than in type 1. It's often caused by:

  • Medications: This includes taking too much medication, including insulin.
  • Food: Eating too few carbohydrates compared to your insulin is a factor.
  • Drinking carbohydrates: Your body absorbs carbs from liquids faster than from solids, so your insulin timing may prove difficult.
  • Physical activity: Exercise lowers your insulin needs.

Note that newer insulins and diabetes medications are less likely to result in hypoglycemia.

No Diabetes

Non-diabetic hypoglycemia can be caused by many things, including:

  • Some medications (beta-blockers, some antibiotics, heart arrhythmia medications)
  • Alcohol consumption
  • Underlying kidney, liver, or metabolic illness
  • Undereating
  • Hormonal deficiencies
  • A rare pancreatic tumor (insulinoma) causing insulin overproduction
  • Recent bariatric surgery
  • Insulin autoimmune syndrome
  • Reactive hypoglycemia

How Is Hypoglycemia Diagnosed?

Hypoglycemia is diagnosed with a blood sugar level test. If your blood sugar is below 70 mg/dL, you have hypoglycemia.

If you don't have diabetes, your healthcare provider will diagnose hypoglycemia with a blood test. You will have to fast overnight before the test. Some tests require you to do a longer fast in a hospital setting. 

How to Test Your Blood Sugar at Home

You can test your blood sugar at home with a glucose meter. To test your blood, wash your hands and insert a test strip into your meter. Using the needle included with the test kit, prick the end of a fingertip. Place the blood droplet on the test strip. The meter will read the blood sugar level from the test strip and display it on a screen. 

What Are the Complications of Hypoglycemia?

If hypoglycemia remains untreated, it can lead to any of the severe symptoms mentioned above, such as seizures, unconsciousness, and, eventually, death. This is why it's critical to treat low blood sugar immediately, no matter the cause.

Hypoglycemia can also be a contributing factor in:

  • Falls
  • Motor vehicle accidents
  • Other injury-causing accidents

Because hypoglycemia isn't a disease but an indication of another problem, it's extremely important that you and your healthcare provider figure out the cause. This is especially true if you don't have diabetes or have diabetes with repeated hypoglycemia episodes.

How Is Hypoglycemia Treated?

Hypoglycemia can usually be treated at home by eating a small snack containing 15 carbohydrates. Check your blood sugar 15 minutes after eating the snack, and repeat if it is not above 70mg/dL. 

You can also take glucose tablets instead of eating a snack.

If your hypoglycemia is severe, you may need a glucagon injection. If you have diabetes, you should always keep a glucagon kit on hand in case your blood sugar becomes dangerously low. The glucagon should be injected into an arm, thigh, or buttocks. Glucagon is also available as a dry nasal spray, which is administered into a nostril.

Treatment if You Pass Out

Severe hypoglycemia can lead to loss of consciousness. If this happens, someone else will need to administer the glucagon injection. Make sure your friends and family members know where you keep your glucagon kit and that they understand how to administer the injection if you lose consciousness.

How Is Hypoglycemia Prevented?

You can prevent low blood sugar by monitoring your blood sugar as recommended by your healthcare provider and making sure you have 15g carbohydrate snacks on hand if your blood sugar begins to trend low. 

Make sure you are eating on a regular schedule and that you are eating consistent amounts. Don't skip meals or snacks and be sure to take your medication as directed. Avoid alcohol or drink in moderation and only with a meal or snack. 

If you are more physically active than usual, you may need to add snacks or adjust your medication. It is especially important to continue monitoring your glucose on days when you are more active than usual.

If you have hypoglycemia often, it's a good idea to keep records of what you eat and how much exercise you've been getting. This can help you spot patterns so you can avoid becoming hypoglycemic in the future.

When to See a Healthcare Provider

When to get medical help for hypoglycemia depends on whether you have diabetes.

If You Don't Have Diabetes

If you don't have diabetes and you have symptoms of hypoglycemia, you should see your healthcare provider right away, even if you're able to get your symptoms to subside.

Being hypoglycemic means something else is going on and you need to find out what that is. Then, you can get treatment before your hypoglycemia becomes life-threatening.

If you still have symptoms after treating your low blood sugar with the above measures, go to the emergency room immediately.

If You Have Diabetes

If you have diabetes, you'll most likely deal with hypoglycemia on occasion. If your blood sugar is below 70 mg/dl, try one of the remedies detailed above or take glucose tablets as directed by the package.

As long as your blood sugar goes back to normal, you can resume your regular activities. However, if you've treated your hypoglycemia and your blood sugar remains low and/or you still have symptoms, contact your healthcare provider as soon as possible.

Visit with your healthcare provider right away if you have symptoms of nocturnal hypoglycemia and/or recurring episodes of hypoglycemia since these can turn into serious, potentially life-threatening problems if they're not treated.

Get emergency help for severe symptoms such as:

  • Behavioral changes
  • Confusion
  • Visual changes
  • Slurred speech
  • Seizures
  • Unconsciousness

Summary

Hypoglycemia, also called low blood sugar, is a potentially life-threatening condition where glucose levels in your blood become lower than what is considered normal. It often occurs as a result of diabetes treatment, but other conditions can cause it, too.

If you have symptoms of hypoglycemia or your blood sugar is less than 70mg/dL, try eating a snack containing 15 grams of carbohydrate. If your symptoms do not improve, repeat every 15 minutes until you feel better or your blood glucose is above 70mg/dL.

See your healthcare provider if you don't have diabetes and you have symptoms of hypoglycemia, or if you have diabetes and you frequently experience low blood sugar or have low blood sugar overnight.

Frequently Asked Questions

  • What causes hypoglycemia unawareness?

    It’s unclear, but the longer you live with diabetes, the more likely you are to become unaware when you have symptoms of hypoglycemia.

    It’s possible that diabetes, especially type 1 diabetes, causes changes in the way the brain uses glucose over time, which impairs the brain’s ability to respond to signs of hypoglycemia. More research is needed, though, to understand the condition.

  • What does a hypoglycemic attack feel like?

    You may feel shaky and weak at first. Other common signs of a hypoglycemic attack include:

    • Sweating
    • Headache
    • Vision changes
    • Sudden mood changes and increased irritability 

    If symptoms aren’t treated, it can lead to confusion, seizures, or a loss of consciousness.

14 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. American Diabetes Association. Hypoglycemia (low blood glucose).

  2. Alsahli M, Gerich JE. Hypoglycemia in patients with diabetes and renal disease. J Clin Med. 2015;4(5):948-64. doi:10.3390/jcm4050948

  3. National Institute of Diabetes and Digestive and Kidney Diseases. Low blood glucose (Hypoglycemia).

  4. American Diabetes Association. 6. Glycemic targets: Standards of medical care in diabetes—2022. Diabetes Care. 2022;45(Supplement 1): S83–S96. doi:10.2337/dc22-S006

  5. Weng N, Luo YW, Xu JD, Zhang Y. Abnormal nocturnal behavior due to hypoglycemia: A case report. Medicine (Baltimore). 2019 Feb;98(6):e14405. doi:10.1097/MD.0000000000014405

  6. Gill, Kirit S et al. Prolonged hypoglycemic effect due to intentional massive insulin glargine overdose. Journal of the Endocrine Society. April-May 2021;5(1):A395-A396. doi:10.1210/jendso/bvab048.805

  7. National Institutes of Health. Hypoglycemia.

  8. Martín-Timón I, Del Cañizo-Gómez FJ. Mechanisms of hypoglycemia unawareness and implications in diabetic patients. World J Diabetes. 2015;6(7):912-26. doi:10.4239/wjd.v6.i7.912

  9. Juvenile Diabetes Research Foundation. Low blood sugar: Symptoms, causes, and treatment for hypoglycemia.

  10. Genetic and Rare Diseases Information Center. Insulin autoimmune syndrome.

  11. National Institutes of Health, U.S. National Library of Medicine: MedlinePlus. Drug-induced low blood sugar.

  12. The Endocrine Society. Hypoglycemia.

  13. Malabu UH, Vangaveti VN, Kennedy RL. Disease burden evaluation of fall-related events in the elderly due to hypoglycemia and other diabetic complications: a clinical review. Clin Epidemiol. 2014 Aug 14;6:287-94. doi:10.2147/CLEP.S66821

  14. Wester M, Bergmann T, Müller-Schilling M, Maier LS, Sossalla ST. Transient hypoglycemia as a rare cause of recurring transient loss of consciousness: a case report. J Med Case Rep. 2021 May 6;15(1):261. doi:10.1186/s13256-021-02844-z

Additional Reading
Rod Brouhard, EMT-P

By Rod Brouhard, EMT-P
Rod Brouhard is an emergency medical technician paramedic (EMT-P), journalist, educator, and advocate for emergency medical service providers and patients.