What is hypoglycemia?

Hypoglycemia is when your blood sugar (blood glucose) level is too low. Glucose is the body's main source of fuel. Carbohydrates are the main source of glucose in our diet. They include rice, potatoes, bread, cereal, fruit, and sweets. The ideal range of fasting morning blood sugar is 70 to 99 mg/dL (milligrams per deciliter). Blood sugar levels lower than 70 mg/dL are too low. They are considered unhealthy. Talk with your healthcare provider about what level is too low for you.

Hypoglycemia may be a condition by itself. Or it may be a complication of diabetes or another disorder. It’s most often seen as a complication of diabetes. This is sometimes called insulin reaction. Hypoglycemia can happen quickly. In adults and children older than age 10, hypoglycemia is uncommon. But it can be a possible side effect of diabetes treatment.

What causes hypoglycemia?

Causes of hypoglycemia in people with diabetes may include:

  • Too much medicine, such as diabetes medicines

  • A missed meal

  • A delayed meal

  • Too little food eaten as compared with the amount of insulin or other medicine taken

Other causes of hypoglycemia are rare. But it may happen in early pregnancy, after strenuous exercise, or during prolonged fasting. Hypoglycemia may also result from abusing alcohol. Or it can be from rare causes, such as a tumor that makes insulin.

What are the symptoms of hypoglycemia?

Symptoms may be a bit different for each person. Symptoms may include:

  • Shakiness

  • Dizziness

  • Sweating

  • Hunger and upset stomach (nausea)

  • Headache

  • Irritability

  • Pale skin color

  • Sudden moodiness or behavior changes, such as crying for no apparent reason

  • Clumsy or jerky movements

  • Trouble paying attention, or confusion

  • Tingling feelings around the mouth

  • Fast heartbeat

  • Blurred vision or vision problems

Hypoglycemia can also happen during sleep. Some signs of hypoglycemia during sleep include:

  • Crying out or having nightmares

  • Finding your clothing or linens damp from perspiration

  • Feeling tired, irritable, or confused after waking

  • Seizures or having trouble waking up

How is hypoglycemia diagnosed?

The healthcare provider will ask about your health history and do a physical exam. You will also need some blood tests to diagnose hypoglycemia.

If you have diabetes and symptoms of hypoglycemia, your healthcare provider will likely diagnose it as a complication of diabetes, or as an insulin reaction. If you don’t have diabetes and have symptoms of hypoglycemia, your provider may:

  • Measure blood glucose levels while you are having the symptoms

  • Watch that the symptoms are eased when you eat foods that have a lot of sugar

You may also have lab tests to measure how much insulin your body makes.

How is hypoglycemia treated?

Treatment will depend on your symptoms, age, and general health. It will also depend on how severe the condition is.

If you have diabetes, the goal of treatment is to stay at a correct blood sugar level. This means testing your blood sugar often. And learning to see the warning signs of low blood sugar. It also means treating the condition quickly. This will be based on past instructions from your healthcare provider.

To treat low blood sugar right away, eat or drink something that has concentrated sugar in it. This includes orange juice, glucose tablets, gel tube, raisins, or a hard candy. A family member can also be trained to give a glucagon shot if you can't take a glucose supplement by mouth.

If you don't have diabetes, your healthcare provider may advise:

  • Not eating foods high in carbohydrates

  • Eating smaller meals more often

  • Having frequent snacks

  • Eating a variety of healthy foods

  • Getting regular exercise

  • Having more testing. This can look for less common causes of hypoglycemia, such as tumors that make insulin.

If left untreated, hypoglycemia can get worse. It can cause confusion, clumsiness, or fainting. Severe hypoglycemia can lead to seizures, coma, and even death.

How can I prevent hypoglycemia?

If you have diabetes, your treatment plan should match the dose and timing of medicine to your usual schedule of meals and activities. Mismatches can result in hypoglycemia. For example, taking a dose of insulin (or other medicine that increases insulin levels) and then skipping a meal could result in hypoglycemia.

To help prevent hypoglycemia, always consider the following if you have diabetes.

Diabetes medicines

Your healthcare provider can explain which diabetes medicines can cause hypoglycemia. He or she can also explain how and when to take medicines. For good diabetes management, take your diabetes medicines in the recommended doses at the recommended times. In some cases, healthcare providers may suggest learning how to adjust medicines to match changes in your schedule or routine.

Meal plans

A registered dietitian can suggest a meal plan that fits your personal preferences and lifestyle. Following this meal plan is important for managing diabetes. Eat regular meals, eat enough food at each meal, and try not to skip meals or snacks. Snacks are very important for some people before going to sleep or exercising. A dietitian can make recommendations for snacks.

Daily activity

To help prevent hypoglycemia caused by physical activity, healthcare providers may advise that you:

  • Check your blood sugar before doing any sports, exercise, or other physical activity. Have a snack if the level is below 100 mg/dL.

  • Adjust medicine as needed before physical activity.

  • Check blood sugar often during and after long periods of physical activity. Have snacks as needed.


Drinking alcohol, especially on an empty stomach, can cause hypoglycemia, even a day or 2 later. Heavy drinking can be very dangerous if you take insulin or medicines that increase insulin production. Only drink alcohol with a snack or meal.

Diabetes management

Intensive diabetes management means keeping your blood sugar as close to the normal range as possible. This is done to prevent long-term problems. But it can raise the risk for hypoglycemia. If you want tight control over your blood sugar, talk with your provider. Ask about ways to prevent hypoglycemia. Ask about how best to treat it if it happens.

When should I call my healthcare provider?

You may tend to have symptoms that seem like hypoglycemia. Then you may need to have your blood sugar tested by your healthcare provider. Before you talk with your provider, write down your questions. This will help you address all of your concerns.

Key points about hypoglycemia

  • Hypoglycemia is when your blood sugar (blood glucose) level is too low.

  • It may be a condition by itself. Or it may be a complication of diabetes or another disorder. It’s most often seen as a complication of diabetes.

  • Symptoms can include shakiness, dizziness, sweating, and headache.

  • To treat low blood sugar right away, eat or drink something that has sugar in it. This includes orange juice or a hard candy.

  • To help prevent hypoglycemia, people with diabetes should think about taking diabetes medicine, eating healthy, staying active, and limiting alcohol.

Next steps

Tips to help you get the most from a visit to your healthcare provider:

  • Know the reason for your visit and what you want to happen.

  • Before your visit, write down questions you want answered.

  • Bring someone with you to help you ask questions and remember what your provider tells you.

  • At the visit, write down the name of a new diagnosis, and any new medicines, treatments, or tests. Also write down any new instructions your provider gives you.

  • Know why a new medicine or treatment is prescribed, and how it will help you. Also know what the side effects are.

  • Ask if your condition can be treated in other ways.

  • Know why a test or procedure is recommended and what the results could mean.

  • Know what to expect if you do not take the medicine or have the test or procedure.

  • If you have a follow-up appointment, write down the date, time, and purpose for that visit.

  • Know how you can contact your provider if you have questions.