Diabetic hypoglycemia


Diabetic hypoglycemia occurs when someone with diabetes doesn't have enough sugar (glucose) in his or her blood. Glucose is the main source of fuel for the body and brain, so you can't function well if you don't have enough.

For many people, low blood sugar (hypoglycemia) is a blood sugar level below 70 milligrams per deciliter (mg/dL), or 3.9 millimoles per liter (mmol/L). But your numbers might be different. Ask your health care provider about the appropriate range to keep your blood sugar (target range).

Pay attention to the early warning signs of hypoglycemia and treat low blood sugar promptly. You can raise your blood sugar quickly by eating or drinking a simple sugar source, such as glucose tablets, hard candy or fruit juice. Tell family and friends what symptoms to look for and what to do if you're not able to treat the condition yourself.


Early warning signs and symptoms

Initial signs and symptoms of diabetic hypoglycemia include:

  • Looking pale (pallor)
  • Shakiness
  • Dizziness or lightheadedness
  • Sweating
  • Hunger or nausea
  • An irregular or fast heartbeat
  • Difficulty concentrating
  • Feeling weak and having no energy (fatigue)
  • Irritability or anxiety
  • Headache
  • Tingling or numbness of the lips, tongue or cheek

Nighttime signs and symptoms

If diabetic hypoglycemia occurs when you're sleeping, signs and symptoms that may disturb your sleep include:

  • Damp sheets or nightclothes due to perspiration
  • Nightmares
  • Tiredness, irritability or confusion upon waking

Severe signs and symptoms

If diabetic hypoglycemia isn't treated, signs and symptoms of hypoglycemia worsen and can include:

  • Confusion, unusual behavior or both, such as the inability to complete routine tasks
  • Loss of coordination
  • Difficulty speaking or slurred speech
  • Blurry or tunnel vision
  • Inability to eat or drink
  • Muscle weakness
  • Drowsiness

Severe hypoglycemia may cause:

  • Convulsions or seizures
  • Unconsciousness
  • Death, rarely

Symptoms can differ from person to person or from episode to episode. Some people don't have any noticeable symptoms. It's also possible you won't have any symptoms of hypoglycemia. It's important to monitor your blood sugar levels regularly and keep track of how you're feeling when your blood sugar is low.

When to see a doctor

Severe hypoglycemia can lead to serious problems, including seizures or unconsciousness, that require emergency care. Make sure your family, friends and co-workers know what to do in an emergency.

Inform people you trust about hypoglycemia. If others know what symptoms to look for, they might be able to alert you to early symptoms. It's important that family members and close friends know where you keep glucagon and how to give it so that a potentially serious situation can be easier to safely manage. Glucagon is a hormone that stimulates the release of sugar into the blood.

Here's some emergency information to give to others. If you're with someone who is not responding (loses consciousness) or can't swallow due to low blood sugar:

  • Don't inject insulin, as this will cause blood sugar levels to drop even further
  • Don't give fluids or food, because these could cause choking
  • Give glucagon by injection or a nasal spray
  • Call 911 or emergency services in your area for immediate treatment if glucagon isn't on hand, you don't know how to use it, or the person isn't responding

If you have symptoms of hypoglycemia several times a week or more, see your health care provider. You may need to change your medication dosage or timing, or otherwise adjust your diabetes treatment regimen.


Low blood sugar is most common among people who take insulin, but it can also occur if you're taking certain oral diabetes medications.

Common causes of diabetic hypoglycemia include:

  • Taking too much insulin or diabetes medication
  • Not eating enough
  • Postponing or skipping a meal or snack
  • Increasing exercise or physical activity without eating more or adjusting your medications
  • Drinking alcohol

Blood sugar regulation

Most of the body's glucose comes from food. The hormone insulin lowers blood sugar (glucose) levels when blood sugar is too high. If you have type 1 or type 2 diabetes and need insulin to control your blood sugar, taking more insulin than you need can cause your blood sugar level to drop too low and result in hypoglycemia.

Your blood sugar can also drop too low if, after taking your diabetes medication, you eat less than usual, or if you exercise more than you typically do, which uses extra glucose. Maintaining the balance between insulin, food and activity isn't always easy. But your health care provider, certified diabetes care and education specialist, and registered dietitian can work with you to try to prevent low blood sugar levels.

Risk factors

Some people have a greater risk of diabetic hypoglycemia, including:

  • People using insulin
  • People taking diabetes drugs called sulfonylureas, such as glipizide (Glucotrol), glimepiride (Amaryl) or glyburide (Diabeta, Glynase)
  • Young children and older adults
  • Those with impaired liver or kidney function
  • People who've had diabetes for a long time
  • People who don't feel low blood sugar symptoms (hypoglycemia unawareness)
  • Those taking multiple medications
  • Anyone with a disability that prevents a quick response to falling blood sugar levels
  • People who drink alcohol


If you ignore the symptoms of hypoglycemia too long, you may lose consciousness. That's because your brain needs glucose to function. Recognize the signs and symptoms of hypoglycemia early, because if untreated, hypoglycemia can lead to:

  • Seizures
  • Loss of consciousness
  • Death

Take your early symptoms seriously. Diabetic hypoglycemia can increase the risk of serious — even deadly — accidents.


To help prevent diabetic hypoglycemia:

  • Monitor your blood sugar. Depending on your treatment plan, you may check and record your blood sugar level several times a week or multiple times a day. Careful monitoring is the only way to make sure that your blood sugar level remains within your target range.
  • Don't skip or delay meals or snacks. If you take insulin or oral diabetes medication, be consistent about the amount you eat and the timing of your meals and snacks.
  • Measure medication carefully and take it on time. Take your medication as recommended by your health care provider.
  • Adjust your medication or eat additional snacks if you increase your physical activity. The adjustment depends on the blood sugar test results, the type and length of the activity, and what medications you take. Follow your diabetes treatment plan when making adjustments.
  • Eat a meal or snack with alcohol, if you choose to drink. Drinking alcohol on an empty stomach can cause hypoglycemia. Alcohol may also cause delayed hypoglycemia hours later, making blood sugar monitoring even more important.
  • Record your low glucose reactions. This can help you and your health care team identify patterns contributing to hypoglycemia and find ways to prevent them.
  • Carry some form of diabetes identification so that in an emergency others will know that you have diabetes. Use a medical identification necklace or bracelet and wallet card.


If you have signs or symptoms of low blood sugar, check your blood sugar level with a blood glucose meter — a small device that measures and displays your blood sugar level. You have hypoglycemia when your blood sugar level drops below 70 mg/dL (3.9 mmol/L).


If you think your blood sugar may be dipping too low, check your blood sugar level with a blood glucose meter. If you have symptoms of low blood sugar but can't check your blood sugar level right away, assume your blood sugar is low and treat for hypoglycemia.

Hypoglycemic management

Eat or drink carbohydrates

Eat or drink something that's mostly sugar or carbohydrates to raise your blood sugar level quickly. Pure glucose — available in tablets, gels and other forms — is the preferred treatment.

Foods with more fat, such as chocolate, don't raise blood sugar as quickly. And diet soft drinks cannot be used to treat an episode of hypoglycemia because they don't have any sugar.

Examples of foods that do raise your blood sugar level quickly include:

  • Four glucose tablets (available without a prescription at most pharmacies)
  • A serving of glucose gel (read the label for amount)
  • Five to 6 pieces of hard candy or jelly beans (check the food label for the exact serving)
  • Four ounces (120 milliliters) of fruit juice or regular — not diet — soda
  • One tablespoon (15 milliliters) of sugar, corn syrup or honey

In general, food or drink with 15 to 20 grams of carbohydrates is often enough to raise your blood sugar levels back into a safe range.

Recheck your blood sugar level

Check your blood sugar level 15 minutes after eating or drinking something to treat your hypoglycemia. If your blood sugar is still low, eat or drink another 15 to 20 grams of carbohydrates. Repeat this pattern until your blood sugar is above 70 mg/dL (3.9 mmol/L).

Have a snack or meal

Have a snack or a meal to keep your blood sugar from dropping again. If you typically take insulin with food, you generally don't need additional insulin if you're eating a snack after having a low blood sugar level. If you're going to eat a meal, however, you may need a reduced dose of insulin to ensure that your blood sugar doesn't rise too quickly.

It's important to try not to overtreat your low blood sugar. If you do, you may cause your blood sugar level to rise too high, which will make you feel thirsty and tired.

Emergency treatment

Glucagon is a hormone that raises blood sugar quickly. It can be lifesaving if someone isn't alert enough to eat or drink something to raise his or her blood sugar. Glucagon is available only by prescription.

Glucagon comes in an emergency syringe kit or as a pre-mixed injection that is ready to use. Glucagon is also available as a powdered nasal spray given in one nostril. Store glucagon as directed on the packaging and be aware of the expiration date. When given to someone who is unconscious, the person should be turned on his or her side to prevent choking in case of vomiting.

About 15 minutes after getting glucagon, the person should be alert and able to eat. If someone doesn't respond within 15 minutes, call emergency medical care. If someone quickly responds to glucagon, it's still recommended that you contact his or her diabetes health care provider promptly.

If you've had a low blood sugar episode that was serious enough to require help from others, your health care provider will likely want to figure out if your insulin or other diabetes medication needs to be adjusted to prevent another serious episode.

Difficult-to-manage hypoglycemia

Some people have frequent and severe hypoglycemia despite medication adjustments. In these circumstances, your health care provider may recommend that you keep your blood sugar in a higher than usual range.

Your provider may also suggest that you use a continuous glucose monitor — a device that measures your blood sugar every few minutes using a sensor inserted underneath the skin. Your health care provider will also likely recommend that you have glucagon with you at all times. Teach people you trust, such as family, friends and close co-workers, how to use it.

Hypoglycemia unawareness

Some people don't have or don't recognize early symptoms of hypoglycemia (hypoglycemia unawareness). If you have hypoglycemia unawareness, your health care provider may recommend a higher glucose target range.

It's also very important to check your blood sugar consistently before going to bed and to have a snack containing carbohydrates before going to sleep if your blood sugar is lower than your bedtime target. Your health care provider may also recommend a continuous glucose monitor that can sound an alarm when your blood sugar is dropping.

Continuous glucose monitor and insulin pump

Self care

Teach people how to help

Inform people you trust, such as family, friends and co-workers, about hypoglycemia. If others know what symptoms to look for, they might be able to alert you to early symptoms. It's important that family members and close friends know where you keep glucagon and how to give it so that a potentially serious situation can be easier to safely manage.

Plan ahead

Always carry a low blood sugar treatment with you, such as glucose tablets, hard candy or gel. Also carry glucagon if it's prescribed for you.

Wear a medical ID

It's a good idea to wear a necklace or bracelet and have a wallet card that identifies you as someone who has diabetes.

Preparing for your appointment

If you have low blood sugar levels several times a week, make an appointment with your health care provider. Together you can determine what's leading to your hypoglycemia and figure out what changes to make to prevent it.

Here's some information to help you get ready for your appointment.

What you can do

  • Be aware of pre-appointment restrictions. Sometimes you need to not eat or drink anything but water for 8 to 12 hours (fast) for blood tests. When you make the appointment, ask if fasting is necessary. If it is, ask what changes you need to make to your diabetes management because you're not eating or drinking.
  • Make a list of your symptoms and how often they occur. It helps to keep a record of your blood sugar readings and low blood sugar reactions so that you and your health care provider can see patterns leading to hypoglycemia.
  • Make a list of key personal information, including major stresses or recent life changes. If you're monitoring your glucose values at home, bring a record of the glucose results, detailing the dates and times of testing.
  • Make a list of medications, vitamins and supplements you take.
  • Create a record of blood glucose meter values. Give your health care provider a written or printed record of your blood sugar levels, times and medication.
  • Take your glucose meter with you. Some meters allow your provider's office to download the recorded glucose values.
  • Write down questions to ask your health care provider. Ask your provider about any parts of your diabetes management plan where you need more information.

Questions you may want to ask include:

  • How often do I need to check my blood sugar?
  • What is my target blood sugar range?
  • How do diet, exercise and weight changes affect my blood sugar?
  • How can I prevent low blood sugar?
  • Do I need to worry about high blood sugar? What are the signs and symptoms I need to watch out for?
  • Do I need a prescription for emergency glucagon?
  • If I continue having hypoglycemia, when do I need to see you again?

Don't hesitate to ask other questions.

What to expect from your doctor

Your health care provider is likely to ask you a number of questions, such as:

  • What symptoms do you notice when you have low blood sugar?
  • How often do you have these symptoms?
  • What do you do to raise your blood sugar levels?
  • What's a typical day's diet like?
  • Are you exercising? If so, how often?
  • Do your family, friends and co-workers know what to do if you have severe hypoglycemia?

Content From Mayo Clinic Updated: 05/05/2022
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