Hypoglycemia

Normal and Target Blood Glucose Ranges (mg/dL)

Types

There are two main types of hypoglycemia.

1. One type is associated with diabetes and happens when there is an imbalance between the insulin taken and the glucose consumed.
2. The other type is not affiliated with diabetes and may be due to medications or other conditions.

Signs and Symptoms

Symptoms of hypoglycemia include

• hunger
• nervousness and shakiness
• anxiety
• perspiration
• weakness
• dizziness or light-headedness
• sleepiness
• confusion
• difficulty concentrating or speaking

If the blood sugar is low enough that the brain cannot get enough glucose to function, patients can lose consciousness and enter a coma, termed hypoglycemic coma. This can be very serious; if it is not treated it can cause stroke or even death, although this is uncommon.

Hypoglycemia can also happen during sleep. Typical symptoms include:

• perspiring at night, resulting in damp pajamas or sheets
• feeling tired, irritable, or confused upon waking
• having nightmares

Patients taking certain medications, such as beta blockers, may not feel the nervous, shaky symptoms that other people feel, a phenomenon called hypoglycemia unawareness. This means that they do not get as much warning as other people before the blood sugar level becomes dangerously low. People with diabetes who are taking these medications need to be especially careful with medications that lower the blood sugar. Formerly, having diabetes was considered a reason not to prescribe beta blockers because of hypoglycemia unawareness, but beta blockers have so many benefits that it is now considered reasonable to prescribe them to diabetes patients who need them.^[1]

Causes

Hypoglycemia related to diabetes

The most common reason for abnormally low blood sugar is associated with diabetes. In people with diabetes, the effects of insulin on the body are drastically diminished, either because the pancreas doesn't produce enough of it (type 1 diabetes) or because the cells are less responsive to it (type 2 diabetes). As a result, glucose builds up in the bloodstream and may reach dangerously high levels. To correct this problem, people with diabetes take insulin or other drugs designed to lower blood sugar levels.

If a person takes too much insulin relative to the amount of glucose in the bloodstream, it can cause the blood sugar level to drop too low, resulting in hypoglycemia. Hypoglycemia may also result from eating less than usual after taking insulin (ingesting less glucose), or exercising more (using up more glucose) than normal.

• All diabetes pills can cause blood sugar to drop too low.
• Glipizide (Glucotrol®), glimepiride (Amaryl®), glyburide(Diabeta®, Glynase PresTab®, Micronase®), and repaglinide (Prandin®) are more likely to cause very low blood sugar.
• Low blood sugar is more likely when you take two or more kinds of diabetes pills.

Hypoglycemia not related to diabetes

There are several ways a person who is not diabetic may become hypoglycemic.

Reactive (post-prandial) hypoglycemia

In reactive hypoglycemia, symptoms appear within four hours after eating a meal. The causes of most cases of reactive hypoglycemia are still open to debate. Some researchers suggest that certain people may be more sensitive to the body's normal release of the hormone epinephrine, which causes many of the symptoms of hypoglycemia. Others believe that deficiencies in glucagon secretion might lead to hypoglycemia.

A few causes of reactive hypoglycemia are certain, but they are uncommon. Gastric (stomach) surgery, for instance, can cause hypoglycemia because food passes so quickly into the small intestine. Also, rare enzyme deficiencies diagnosed early in life, such as hereditary fructose intolerance, may cause reactive hypoglycemia.

Fasting (post-absorptive) hypoglycemia

Causes of fasting hypoglycemia, in which the body is unable to keep glucose levels up between meals, include certain medications, alcohol, critical illnesses, hormonal deficiencies, some kinds of tumors, and certain conditions occurring in infancy and childhood.

• Medications. Accidentally taking another person's oral diabetes medication is a common cause of hypoglycemia. Other medications may cause hypoglycemia, especially in children or in people with kidney failure. One example is quinine, which is used to treat leg cramps and malaria. Other medications that can cause hypoglycemia include:
  • salicylates, including aspirin, when taken in large doses
  • sulfa medicines, which are used to treat infections
  • pentamidine, which treats pneumonia caused by Pneumocystis carinii^[2]

• Excessive alcohol consumption. Drinking, especially binge drinking or drinking heavily without eating, can block the liver from releasing stored glucose into the bloodstream, causing hypoglycemia. The body's breakdown of alcohol interferes with the liver's efforts to raise blood glucose. Hypoglycemia caused by excessive drinking can be very serious and even fatal. Children are especially susceptible to hypoglycemia from drinking alcohol, as, for example, if a curious toddler drinks a colorful cocktail left over after a party.

• Critical illnesses. Severe illnesses of the liver, such as drug-induced hepatitis, can cause hypoglycemia. Disorders of the kidney, which can keep the body from properly excreting medications, can affect glucose levels. Long-term starvation, as may occur in the eating disorder anorexia nervosa, can result in the depletion of substances the body needs to produce sugar, causing hypoglycemia. Sepsis (overwhelming infection) is another cause of hypoglycemia. In these cases, treatment of the low glucose is aimed at treating its underlying cause.

• Tumors. A rare tumor of the pancreas called an insulinoma causes overproduction of insulin, resulting in hypoglycemia.^[3] Other tumors may result in excessive production of insulin-like substances. Or, the tumors themselves may use up too much glucose. Enlargement of the beta cells of the pancreas that produce insulin (nesidioblastosis) may result in excessive insulin release, causing hypoglycemia. People who have undergone gastric bypass surgery are at risk of this condition. Treatment involves both short-term steps to correct the hypoglycemia and medical or surgical measures to remove the tumor.

• Hormonal or endocrine deficiencies. Certain disorders of the adrenal glands and the pituitary gland can result in a deficiency of key hormones such as cortisol, growth hormone, glucagon, or epinephrine that regulate glucose production. Decreased secretion of these hormones may lead to fasting hypoglycemia, but typically children with these disorders are more prone to hypoglycemia than are adults. Laboratory tests for hormone levels can determine a diagnosis and treatment. Hormone replacement therapy may be advised.

Diagnosis

Diagnosing diabetic hypoglycemia

Diabetic hypoglycemia can be diagnosed by using a blood glucose meter to check the glucose level. Hypoglycemia is confirmed if the blood sugar is 70 mg/dL or below.

Diagnosing hypoglycemia not related to diabetes

To diagnose reactive hypoglycemia, the doctor uses Whipple's triad, a diagnostic approach named after the American surgeon Allen Whipple. Whipple's triad consists of the following three factors.

1. Signs and symptoms of hypoglycemia. The signs and symptoms of hypoglycemia may not be exhibited during the initial visit to the doctor. In this case, the doctor may require an overnight fast. This will allow hypoglycemic symptoms to occur so that he or she can make a diagnosis. An extended fast in a hospital setting may also be necessary. Or, if symptoms occur after a meal, the doctor will want to test glucose levels after a meal.
2. Documentation of low blood glucose when the signs and symptoms occur. The doctor will check a blood sample.
3. Disappearance of the signs and symptoms. The third part of the diagnostic triad involves seeing whether symptoms subside after the blood glucose level returns to 70 mg/dL or higher (after eating or drinking). A blood glucose level of less than 70 mg/dL at the time of symptoms, then relief of the symptoms after eating, will confirm the diagnosis.

A physical examination and medical history will be performed, as the doctor will want to determine what medications are used, whether alcohol is used excessively and whether the patient has a critical illness. This will help the doctor confirm the diagnosis and determine the likely cause.

The oral glucose tolerance test is no longer used to diagnose hypoglycemia; experts now know that the test can actually trigger hypoglycemic symptoms.

Fasting hypoglycemia is diagnosed from a blood sample that shows a blood glucose level of less than 50 mg/dL after an overnight fast, between meals, or after exercise.

Treatment

If low blood glucose is suspected, a blood glucose meter can be used to check the level. If it is 70 mg/dL or below, one of the following "quick fix" foods should be eaten right away to raise blood glucose:

Check your blood glucose again in 15 minutes. Eat another 10 to 15 grams of carbohydrate every 15 minutes until your blood glucose is above 70 mg/dL.

Eating or drinking an item from the list on this page will keep your glucose up for only about 30 minutes. So if your next planned meal or snack is more than 30 minutes away, you should go ahead and eat something like crackers and a tablespoon of peanut butter.

In your glucose logbook or record sheet, write down the numbers and the times when low levels happen. Think about what may be causing them. If you think you know the reason, write it beside the numbers you recorded. You may need to call your health care provider to talk about changing your diet, activity, or diabetes medicine.

Tell family members, close friends, teachers, and people at work that you have diabetes. Tell them how to know when your blood glucose is low. Show them what to do if you can’t treat yourself. Someone will need to give you fruit juice, soda pop (not diet), or sugar.

If you can’t swallow, someone will need to give you a shot of glucagon and call for help. Glucagon is a prescription medicine that raises the blood glucose and is injected like insulin. If you take insulin, you should have a glucagon kit handy. Teach family members, roommates, and friends when and how to use it.

After 15 minutes, blood glucose should be checked again to make sure that it is no longer too low. If it is still too low, another serving is recommended. These steps can be repeated until the blood glucose is at least 70. Then, if it will be an hour or more before the next meal, the person should have a snack.

If the low blood sugar was caused by a long-acting diabetes pill, the person may need to stay in the hospital for close monitoring until the pill wears off, usually for about a day.

For people who take insulin or a diabetes medication that can cause hypoglycemia, carrying one of the quick-fix foods is recommended at all times. Glucose tablets are convenient and easy to carry. Wearing a medical identification bracelet or necklace is also a good idea, in the event that symptoms become too severe for the person to help themselves.

Exercise can also cause hypoglycemia, so checking the blood glucose before exercising is recommended.

Severe hypoglycemia can lead to unconsciousness. In these extreme cases when the person loses consciousness and cannot eat, glucagon can be injected to quickly raise the blood glucose level. This method is particularly important for people with type 1 diabetes. The person's family, friends, and co-workers will need to be taught how to give a glucagon injection in an emergency. Glucagon is often used on ambulances if intravenous lines cannot be started.

To prevent and treat reactive hypoglycemia, some health professionals recommend taking the following steps:

• eat small meals and snacks about every three hours
• exercise regularly
• eat a variety of foods, including meat, poultry, fish, or non-meat sources of protein; starchy foods such as whole-grain bread, rice, and potatoes; fruits; vegetables; and dairy products
• choose high-fiber foods
• avoid or limit foods high in sugar, especially on an empty stomach

The doctor can refer the patient to a registered dietitian for personalized meal planning advice. Although some health professionals recommend a diet high in protein and low in carbohydrates, studies have not proven the effectiveness of this kind of diet for reactive hypoglycemia.

Prevention

• Healthy meal plan. A registered dietitian can help develop a meal plan that fits a person's preferences, schedule, and lifestyle. This meal plan should be followed as closely as possible. Eating regular meals, having enough food at each meal, and trying not to skip meals or snacks is recommended. If a person takes their insulin but then skips a meal, the insulin will still lower the blood glucose, but it will not find the food it is designed to break down. This mismatch can result in hypoglycemia. Also, medications and insulin should be taken in the recommended doses and at the recommended times.

• Daily activity level. Talking to a health care professional about having a snack or adjusting medication before sports or exercise is recommended. Having a snack before more activity than usual or before doing something that is not part of the normal routine—shoveling snow, for example—may also be recommended.

• Alcoholic beverages. Drinking, especially on an empty stomach, can cause hypoglycemia, even a day or two later. Eating a snack or meal while drinking an alcoholic beverage is recommended.

Prevention of hypoglycemia while driving a vehicle is especially important. Checking blood glucose frequently and snacking as needed to keep blood glucose above 70 mg/dL will help prevent accidents.

• Keep a balance

Try to stay close to your usual schedule of eating, activity, and medicine. If you’re late getting a meal or if you’re more active than usual, you may need an extra snack. See Managing Your Diabetes at Work, School, and in Travel for more ideas about managing your diabetes.

• Check your blood glucose

Keeping track of your blood glucose is a good way to know when it tends to run low. Show your logbook or record sheet to your health care providers. Be sure to let them know if you’re having a number of low glucose readings a week.

• To be safe, always check your glucose before doing any of these things:

• Driving a vehicle.
  
• Using heavy equipment.
  
• Being very physically active.
  
• Being active for a long time.

• Always carry along some food with carbohydrates in it.

• Be prepared Always carry some type of carbohydrate sugar food or drink with you so you’ll be ready at any time to treat a low glucose level. See the table "Foods and Liquids for Low Blood Glucose" for snacks that have 10–15 grams of carbohydrate.

• Always wear something (like an identification bracelet) that says you have diabetes. Carry a card in your wallet that says you have diabetes and tells if you use medicine to treat it.

• Wear something that lets others know you have diabetes, in case of an emergency.
  

Signs and symptoms of hypoglycemia can vary from person to person. An individual should learn his or her own signs and be able to describe them to friends and family. School staff should also be informed about signs, symptoms, and treatment for children with diabetes.

If hypoglycemic episodes occur several times a week, a health care provider should be contacted, as a change in treatment plan may be required: less medication or a different medication, a new schedule for insulin shots or medication, a different meal plan, or a new exercise plan.

Prevention of reactive hypoglycemia

Reactive hypoglycemia with demonstrably low blood glucose levels is most often a predictable nuisance which can be avoided by consuming fat and protein with carbohydrates, by adding morning or afternoon snacks, and reducing alcohol intake.

Fasting hypoglycemia without demonstrably low glucose levels at the time of symptoms can be more difficult to manage. Many people find improvement by changing eating patterns (smaller meals, avoiding excessive sugar, mixed meals rather than carbohydrates by themselves), reducing intake of stimulants such as caffeine, or by making lifestyle changes to reduce stress.

Hypoglycemia in Infants and Children

Children rarely develop hypoglycemia. If they do, causes may include:

• Brief intolerance to fasting, often in conjunction with an illness that disturbs regular eating patterns. Children usually outgrow this tendency by age 10.
• Hyperinsulinism, which is the excessive production of insulin. This condition can result in transient neonatal hypoglycemia, which is common in newborns of mothers with diabetes. Persistent hyperinsulinism in infants or children is a complex disorder that requires prompt evaluation and treatment by a specialist.
• Enzyme deficiencies that affect carbohydrate metabolism. These deficiencies can interfere with the body's ability to process natural sugars, such as fructose and galactose, glycogen, or other metabolites.
• Hormonal deficiencies such as lack of pituitary or adrenal hormones.

Clinical Trials

For a list of American government-sponsored clinical trials researching hypoglycemia, visit Hypoglycemia Clinical Trials.

Research

In the United States, the National Institute of Diabetes and Digestive and Kidney Diseases conducts and supports research in diabetes, glucose metabolism, and related conditions. Researchers supported by NIDDK are investigating topics such as the following:

• What are the causes of hypoglycemia?
• Can transplanting islet cells eliminate hypoglycemia?
• Can laparoscopy (a surgical procedure) be used to find and remove insulinomas (insulin-producing tumors)?
• Do new frequent-glucose-monitoring devices help prevent hypoglycemia?
• Why do repeated episodes of hypoglycemia lead to loss of awareness of hypoglycemia symptoms?

References

1. ↑ Dunne F, Kendall MJ, Martin U. Beta-blockers in the management of hypertension in patients with type 2 diabetes mellitus: is there a role? Drugs. 2001;61(4):429-35. Abstract
2. ↑ Assan R, Perronne C, Assan D, Chotard L, Mayaud C, Matheron S, Zucman D. Pentamidine-induced derangements of glucose homeostasis. Determinant roles of renal failure and drug accumulation. A study of 128 patients. Diabetes Care. 1995 Jan;18(1):47-55. Abstract
3. ↑ Goode AW. Insulinoma. J R Soc Med. 1989 Jul;82(7):383-4. Abstract | Full Text

External Links

American Diabetes Association

Juvenile Diabetes Research Foundation International