Diabetes Health Center

Low blood sugar (hypoglycemia) occurs when the sugar (glucose) level in the blood drops below what the body needs to function normally. Some pills for diabetes can cause low blood sugar. If you want to know how to deal with low blood sugar caused by insulin, see:

Diabetes: Dealing with low blood sugar from insulin.

Key points

• Low blood sugar as a side effect of oral diabetes medicines usually causes mild symptoms, such as sweating, shakiness, and hunger.
• Taking too many of your diabetes pills in one day, not eating enough food, or doing strenuous physical activity can cause your blood sugar level to drop below your target range.
• If your blood sugar is low and you don't eat anything, it may drop to a very low level. Keep some hard candy, raisins, or other quick sugar foods with you at all times. Eat some at the first sign of low blood sugar.
• Test your blood sugar often so you do not have to guess when it is low.
• Teach your friends and coworkers what to do if your blood sugar is very low.

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 milligrams per deciliter (mg/dL), you most likely will have symptoms, such as feeling tired, weak, or shaky. Symptoms of low blood sugar usually 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 something that contains sugar, your symptoms may last only a short time. If you have had diabetes for many years, you may not realize your blood sugar is low until it drops very low. 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 (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.

What causes low blood sugar?

Low blood sugar levels can be caused by having too much insulin in your body and/or not enough sugar in your blood. This can happen with some oral medicines used to treat diabetes and also with insulin shots. This is more likely to happen if you eat less food than usual, exercise, or do intense physical work. Very low blood sugar levels most often develop rapidly (in 10 to 15 minutes) when a person has skipped a meal and is doing intense physical work. Reduced kidney function can prolong the action of diabetes medicine, possibly making low blood sugar levels more frequent.

Usually, blood sugar levels in people who take diabetes medicine drop only low enough to cause mild symptoms. Very low blood sugar levels usually do not occur in people with diabetes who do not take insulin shots. Some pills used to treat type 2 diabetes are more likely to cause low blood sugar than others.

Low blood sugar levels can occur if you:

• Take too many of your sulfonylurea pills or meglitinide pills in a day or take your doses too close together.
• Continue to take your full dose of sulfonylurea pills or meglitinide pills when you are not going to eat your usual amount of food.
• Exercise strenuously without eating enough food.
• Drink too much alcohol, especially on an empty stomach.
• Take certain other medicines that lower blood sugar. Some medicines that you can buy without a prescription can affect blood sugar. Talk with your doctor about your prescription and nonprescription medicines and the risk of developing very low blood sugar levels.

Even mild low blood sugar can affect the way you think and respond to things around you. And mild low blood sugar can quickly drop to a more dangerous level.

If your blood sugar drops 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 that your blood sugar is too low, and you may not be aware that you need to eat food 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, your brain may not work properly. This can cause an accident if you are driving a car or operating other machinery.

If your blood sugar level drops below 20 mg/dL, which is considered severe low blood sugar, you can lose consciousness. If you do not receive prompt emergency care, you may go into a coma, have a seizure, heart attack, or stroke, and possibly die.

Here are some ways you can manage low blood sugar.

Be prepared

• Keep some quick-sugar foods with you at all times. The quick-sugar foods list gives some examples of foods and how much you need to eat to raise your blood sugar. The foods on this list will help raise your blood sugar by about 30 mg/dL within about 15 minutes. If you are at home, you most likely will already have something close at hand that contains sugar, such as table sugar or fruit juice. Carry some hard candy or glucose tablets when you are away from home.
• Know the symptoms of low blood sugar. Post them where you will see the list often. And carry a copy in your wallet or purse. Be sure that your partner and others concerned know your early symptoms, including the signs of low blood sugar at night.
• Wear medical identification, such as a medical alert bracelet , to let people know that you have diabetes. People will know that you have diabetes and will get help for you if needed.
• Teach others (at work and at home) how to check your blood sugar in case you cannot check it yourself. Keep the instructions for using your blood sugar (glucose) meter with the meter, so the person can review the instructions if needed.
• Teach other people (at work and at home) what to do in case your blood sugar becomes very low. Post information on emergency care for low blood sugar in a convenient place so that those around you can take the proper steps when your blood sugar is very low.

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.
• Follow the steps for dealing with low blood sugar when you first develop your symptoms of low blood sugar or when your blood sugar level is below your target range (usually below 70 mg/dL). Encourage others to tell you if they notice you are developing signs of low blood sugar.
• Keep a record. Write down your symptoms and how you treated your low blood sugar. Use the low blood sugar level record(What is a PDF document?).
• Notify your doctor if you are having frequent low blood sugar problems. Your pills for diabetes may need to be adjusted or changed.

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

If you have questions about this information, take it with you when you visit your doctor. You may want to mark areas or make notes in the margins where you have questions.