Hypoglycemia is low blood sugar (glucose). Hypoglycemia may be a condition by itself, or it may be a complication of diabetes or another disorder.
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, which may be a possible side effect of diabetes treatment. Hypoglycemia can happen quickly and must be treated quickly.
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 different for each person. Symptoms may include:
Hunger and upset stomach (nausea)
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
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 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 the underlying cause and 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 being aware of 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. Check your blood sugar again in 15 minutes to see if it's back in the normal range. If it's still low, take a repeat dose of concentrated sugar. When your blood sugar has returned to normal, eat a regular snack or meal.
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, which 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.
Your healthcare provider can explain which diabetes medicines can cause hypoglycemia. They 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.
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 and eat enough food at each meal. 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.
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. This can even happen a day or two 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.
Intensive diabetes management means keeping your blood sugar as close to the normal range as possible. This is done to prevent long-term problems. If you want tight control over your blood sugar, talk with your healthcare provider. Ask about ways to prevent hypoglycemia and how to best treat it quickly if it happens.
When should I call my healthcare provider?
Call your healthcare provider right away if any of these symptoms of low blood sugar occur and they have not gone away with the above measures.
Feeling anxious or restless
Call 911 if any of the following occur and don't resolve promptly with the above measures:
Lightheadedness, dizziness, or loss of consciousness
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 take diabetes medicine that is properly timed with meals, eat healthy, stay active, and limit alcohol.
These tips 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.
News & Publications
Quantity and Characteristics of Waste at a Level I Trauma Center
The purpose of this study was to quantify and describe the amount of waste generated by an Emergency Department, identify deviations from waste policy and explore areas for waste reduction.
The Climate-Smart Emergency Department: A Primer
Our publication keeps health care professionals up to date on the latest research and clinical advances from Mass General.
Research Institute Blog
News and notes from the largest hospital-based research program in the United States
A podcast devoted to uncovering the stories of Mass General's relentless pursuit to break boundaries and provide exceptional care
The Patient Gateway provides secure online access to your health information whenever you need it. Check upcoming appointments, communicate with your doctor’s office, review medications and pay medical bills—all seamlessly online 24/7.