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Mayo Clinic Health Library

Diabetic hypoglycemia

Updated: 04-03-2020

Overview

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.

Low blood sugar (hypoglycemia) is defined as a blood sugar level below 70 milligrams per deciliter (mg/dL), or 3.9 millimoles per liter (mmol/L).

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 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.

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Symptoms

Early warning signs and symptoms

Initial signs and symptoms of diabetic hypoglycemia include:

  • Shakiness
  • Dizziness
  • Sweating
  • Hunger
  • Fast heartbeat
  • Inability to concentrate
  • Confusion
  • Irritability or moodiness
  • Anxiety or nervousness
  • Headache

Nighttime signs and symptoms

If diabetic hypoglycemia occurs when you're sleeping, signs and symptoms that may awaken you 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 severe hypoglycemia can occur. These include:

  • Clumsiness or jerky movements
  • Inability to eat or drink
  • Muscle weakness
  • Difficulty speaking or slurred speech
  • Blurry or double vision
  • Drowsiness
  • Confusion
  • 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, so 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.

If you're with someone who 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 — a hormone that stimulates the release of sugar into the blood — through injection or nasally
  • Call 911 or emergency services in your area for immediate treatment if glucagon isn't on hand

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

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Causes

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

The hormone insulin lowers blood sugar 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 (most of the body's glucose comes from food), or if you exercise more than you normally do, which uses extra glucose. Maintaining the balance between insulin, food and activity isn't always easy, but your doctor or diabetes educator can work with you to try to prevent low blood sugar levels.

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Risk factors

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

  • People using insulin
  • People taking certain oral diabetes drugs (sulfonylureas)
  • Young children and older adults
  • Those with impaired liver or kidney function
  • People who've had diabetes for a longer 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
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Complications

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.

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Prevention

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 doctor.
  • 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.
  • 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.
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Diagnosis

If you have signs or symptoms of low blood sugar, check your blood sugar levels 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).

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Treatment

Hypoglycemic management

If you think your blood sugar may be dipping too low, check your blood sugar level with a blood glucose meter. Then eat or drink something that's mostly sugar or carbohydrates to raise your blood sugar level quickly. Pure glucose — found 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 six 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 grams of carbohydrates is often enough to raise your blood sugar levels back into a safe range.

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

When you feel better, have a snack or a meal to keep your blood sugar from dropping again. If you normally take insulin with food, you generally don't need additional insulin if you're eating a snack after having a low blood sugar. 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.

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.

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. And high blood sugar levels increase your risk of long-term diabetes complications if you have them often.

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 nasal treatment. 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 doctor promptly.

If you've had a low blood sugar episode that was serious enough to require help from others, your doctor will 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 doctor may recommend that you keep your blood sugar in a higher than normal range.

He or she may also suggest that you use a continuous glucose monitor — a device that measures your blood sugar every few minutes via a sensor inserted underneath the skin. Your doctor will also likely recommend that you have glucagon with you at all times.

Hypoglycemia unawareness

Some people don't have or don't recognize early symptoms of hypoglycemia (hypoglycemia unawareness). If you have hypoglycemia unawareness, you may need to aim for 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 doctor may also recommend a continuous glucose monitor that can sound an alarm when your blood sugar is dropping.

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Lifestyle and home remedies

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 how to administer glucagon 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.

Wear a medical ID

It's a good idea to wear a bracelet that identifies you as someone who has diabetes.

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Preparing for an appointment

If you have low blood sugar levels several times a week, make an appointment with your doctor. 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 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.
  • Write down your symptoms and how often they occur. It may help to keep a record of your blood sugar readings and low blood sugar reactions so that you and your doctor can see patterns leading to hypoglycemia.
  • Write down 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.
  • List medications, vitamins and supplements you take.
  • Create a record of metered glucose values. Give your doctor a written or printed record of your blood glucose values, times and medication.
  • Take your glucose meter with you. Some meters allow your doctor's office to download the recorded glucose values.
  • Write down questions to ask your doctor. Be clear about aspects of your diabetes management that you need clarified.

For diabetic hypoglycemia, 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 doctor 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?
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