Low blood sugar (hypoglycemia) means that the level of sugar (glucose) in your blood has dropped below what your body needs to function normally. When your blood sugar level drops below 70 mg/dL, you may have symptoms, such as feeling tired, weak, or shaky. Reference Symptoms of low blood sugar can develop quickly.

• If your blood sugar level drops just slightly below your target range, you may have symptoms of mild low blood sugar. If you eat Reference something that contains sugar, these symptoms may last only a short time. If you have had diabetes for many years, you may not always notice symptoms of mild low blood sugar. This is called hypoglycemia unawareness.
• If your blood sugar level continues to drop (usually below 40 mg/dL), your behavior may change. Symptoms of moderate low blood sugar may start. You may become too weak or confused to eat something to raise your blood sugar level.
• If your blood sugar level drops very low (usually below 20 mg/dL), you may lose consciousness or have a seizure. If you have symptoms of severe low blood sugar, you need medical care immediately.

Sometimes people with diabetes have low blood sugar levels during the night. If your blood sugar level drops during the night, you may wake up in a cold sweat and feel weak or you may sleep through it. Your body may use stored sugar to raise your blood sugar level back toward your target range. If this happens, you most likely will wake up in the morning with a headache and possibly high blood sugar.

What causes low blood sugar?

Low blood sugar (hypoglycemia) can develop rapidly (within 10 to 15 minutes). It can occur if you:

• Take too much insulin.
• Skip or delay a meal or snack.
• Exercise too much without eating enough food.
• Drink too much alcohol, especially on an empty stomach.
• Take certain Reference medicines that lower blood sugar. Some medicines that you can buy without a prescription can affect blood sugar levels. Talk with your doctor about your prescription and nonprescription medicines and whether they may increase your risk of developing very low blood sugar levels.
• Start your menstrual period. The hormonal changes may affect how insulin works.

You may have symptoms of low blood sugar if your blood sugar drops from a high level to a lower level. For example, if your blood sugar level has been higher than 300 mg/dL for a week or so and the level drops suddenly to 100 mg/dL, you may have symptoms of low blood sugar. But if you have had diabetes for many years, you may not have symptoms of low blood sugar until your blood sugar level is very low.

If untreated, very low blood sugar can lead to serious illness and death.

When your blood sugar level falls below 70 mg/dL (55 mg/dL if you are pregnant), your body reacts like it does when you feel very afraid, angry, or anxious. You may feel weak, shaky, and/or sweaty. But if you eat Reference something that contains sugar, your blood sugar level most likely will rise. An emergency likely will not develop, and you will not have any long-lasting effects from having low blood sugar.

If your blood sugar continues to drop (below 40 mg/dL), your brain may receive too little sugar to work properly and your judgment and muscle coordination will be affected. These are symptoms of moderate low blood sugar. You may not realize your blood sugar is too low, and you may not be aware that you need to eat food with sugar to raise the level. Someone else may have to help you eat or drink something to raise your blood sugar level. If you do not get help, you could get in an accident if you are driving a car or operating other machinery. If you are pregnant, low blood sugar can harm your baby.

If your blood sugar continues to drop (below 20 mg/dL), you can lose consciousness. If you do not receive prompt emergency care, you may have a seizure.

A low blood sugar level may soon recur, even though it has been treated. Check your blood sugar often after a low level has been treated to make sure your blood sugar returns to normal.

Here are some ways you can manage low blood sugar.

Be prepared

Always be prepared for the possibility of having a low blood sugar level.

• Keep some quick-sugar foods with you at all times. If you are at home, you will probably already have something close at hand that contains sugar, such as table sugar or fruit juice. Carry some hard candy or glucose tablets with you when you are away from home. Reference Quick-sugar foods are foods you need to eat to raise your blood sugar. These foods will help raise your blood sugar by about 30 mg/dL in 15 minutes.
• Know the Reference symptoms of low blood sugar, such as sweating, blurred vision, and confusion. Post a list of the symptoms where you will see it often, and carry a copy in your wallet or purse. Add any symptoms you have noticed that may not be on the list. Be sure that your partner (and others) knows your early symptoms, including the signs of low blood sugar at night.
• Wear medical identification. Always wear medical identification, such as a Reference medical alert bracelet Opens New Window Reference Opens New Window, to let people know that you have diabetes. In case your blood sugar drops very low and you need help, people will know that you have diabetes and will get help for you if necessary.
• Keep Reference glucagon Opens New Window on hand. If you become unconscious when your blood sugar is very low, someone may need to give you a shot of glucagon to raise your blood sugar. Be sure someone knows how to give you the shot. Have the person practice by giving you your insulin shot once or twice a month. This will help the person be confident if he or she has to give you a shot of glucagon in an emergency. Keep the instructions for Reference how to give glucagon with the medicine. Also, check the expiration date on your glucagon. Most kits need to be replaced every 6 months.
• Teach others (at work and at home) how to check your blood sugar in case you cannot check it yourself. Have instructions for how to use your blood sugar (glucose) meter to check your blood sugar with the meter so the person can review the instructions.
• Teach other people (at work and at home) what to do in case your blood sugar becomes very low. Post information on Reference emergency care for low blood sugar in a convenient place at home and at work. Go over with others the steps they need to take when your blood sugar is very low.
• Take Reference precautions when you are driving and do not drive if your blood sugar is below 70 milligrams per deciliter (mg/dL).

Treat low blood sugar early

Treat low blood sugar levels as soon as you (or someone else) notice the symptoms.

• Check your blood sugar often. If you have had diabetes for many years, you may not have symptoms until your blood sugar is very low. Checking your blood sugar regularly and also whenever you think it may be low will take the guesswork out of treating low blood sugar levels.
• Follow your doctor's instructions for Reference dealing with low blood sugar when you first develop your symptoms of low blood sugar or when your blood sugar level is below 70 mg/dL. Encourage others to tell you if they notice you are developing signs of low blood sugar.
• Keep a record (What is a Reference PDF Opens New Window document?) of low blood sugar levels. Write down your symptoms and how you treated your low blood sugar. Look for patterns in when and what you ate, your activity (especially if more than usual), and medicine that could have caused the low blood sugar.
• Notify your doctor. Let her or him know if you are having low blood sugar problems. Your insulin dosage may need to be adjusted.

Now that you have read this information, you are ready to start dealing with low blood sugar levels effectively.

Talk with your health professional

If you have questions about this information, take it with you when you visit your doctor or certified diabetes educator. You may want to write down any questions you have.

If you don't already have glucagon at home, ask your doctor for a prescription. Make sure someone knows how to give you a glucagon shot if an emergency develops. You may want to have two glucagon kits so that if one gets used, you have a backup.

If you would like more information on dealing with low blood sugar levels, the following resources are available:

Organization

More information about diabetes can be found in these topics:

• Reference Type 1 Diabetes
• Reference Type 1 Diabetes: Children Living With the Disease
• Reference Type 2 Diabetes
• Reference Type 2 Diabetes in Children
• Reference Gestational Diabetes

Return to topic: