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The condition called hypoglycemia is literally translated as low blood sugar. Hypoglycemia occurs when blood sugar (or blood glucose) concentrations fall below a level necessary to properly support the body's need for energy and stability throughout its cells.


Carbohydrates are the main dietary source of the glucose that is manufactured in the liver and absorbed into the bloodstream to fuel the body's cells and organs. Glucose concentration is controlled by hormones, primarily insulin and glucagon. Glucose concentration also is controlled by epinephrine (adrenalin) and norepinephrine, as well as growth hormone. If these regulators are not working properly, levels of blood sugar can become either excessive (as in hyperglycemia) or inadequate (as in hypoglycemia). If a person has a blood sugar level of 50 mg/dl or less, he or she is considered hypoglycemic, although glucose levels vary widely from one person to another.
Hypoglycemia can occur in several ways.

Drug-induced hypoglycemia

Drug-induced hypoglycemia, a complication of diabetes, is the most commonly seen and most dangerous form of hypoglycemia.
Hypoglycemia occurs most often in diabetics who must inject insulin periodically to lower their blood sugar. While other diabetics also are vulnerable to low blood sugar episodes, they have a lower risk of a serious outcome than insulin-dependant diabetics. Unless recognized and treated immediately, severe hypoglycemia in the insulin-dependent diabetic can lead to generalized convulsions followed by amnesia and unconsciousness. Death, though rare, is a possible outcome.
In insulin-dependent diabetics, hypoglycemia known as an insulin reaction or insulin shock can be caused by several factors. These include overmedicating with manufactured insulin, missing or delaying a meal, eating too little food for the amount of insulin taken, exercising too strenuously, drinking too much alcohol, or any combination of these factors.

Ideopathic or reactive hypoglycemia

Ideopathic or reactive hypoglycemia (also called postprandial hypoglycemia) occurs when some people eat. A number of reasons for this reaction have been proposed, but no single cause has been identified.
In some cases, this form of hypoglycemia appears to be associated with malfunctions or diseases of the liver, pituitary, adrenals, liver, or pancreas. These conditions are unrelated to diabetes. Children intolerant of a natural sugar (fructose) or who have inherited defects that affect digestion also may experience hypoglycemic attacks. Some children with a negative reaction to aspirin also experience reactive hypoglycemia. It sometimes occurs among people with an intolerance to the sugar found in milk (galactose), and it also often begins before diabetes strikes later on.

Fasting hypoglycemia

Fasting hypoglycemia sometimes occurs after long periods without food, but it also happens occasionally following strenuous exercise, such as running in a marathon.
Other factors sometimes associated with hypoglycemia include:
  • pregnancy
  • a weakened immune system
  • a poor diet high in simple carbohydrates
  • prolonged use of drugs, including antibiotics
  • chronic physical or mental stress
  • heartbeat irregularities (arrhythmias)
  • allergies
  • breast cancer
  • high blood pressure treated with beta-blocker medications (after strenuous exercise)
  • upper gastrointestinal tract surgery.

Causes and symptoms

When carbohydrates are eaten, they are converted to glucose that goes into the bloodstream and is distributed throughout the body. Simultaneously, a combination of chemicals that regulate how our body's cells absorb that sugar is released from the liver, pancreas, and adrenal glands. These chemical regulators include insulin, glucagon, epinephrine (adrenalin), and norepinephrine. The mixture of these regulators released following digestion of carbohydrates is never the same, since the amount of carbohydrates that are eaten is never the same.
Interactions among the regulators are complicated. Any abnormalities in the effectiveness of any one of the regulators can reduce or increase the body's absorption of glucose. Gastrointestinal enzymes such as amylase and lactase that break down carbohydrates may not be functioning properly. These abnormalities may produce hyperglycemia or hypoglycemia, and can be detected when the level of glucose in the blood is measured.
Cell sensitivity to these regulators can be changed in many ways. Over time, a person's stress level, exercise patterns, advancing age, and dietary habits influence cellular sensitivity. For example, a diet consistently overly rich in carbohydrates increases insulin requirements over time. Eventually, cells can become less receptive to the effects of the regulating chemicals, which can lead to glucose intolerance.
Diet is both a major factor in producing hypoglycemia as well as the primary method for controlling it. Diets typical of western cultures contain excess carbohydrates, especially in the form of simple carbohydrates such as sweeteners, which are more easily converted to sugar. In poorer parts of the world, the typical diet contains even higher levels of carbohydrates. Fewer dairy products and meats are eaten, and grains, vegetables, and fruits are consumed. This dietary trend is balanced, however, since people in these cultures eat smaller meals and usually use carbohydrates more efficiently through physical labor.
Early symptoms of severe hypoglycemia, particularly in the drug-induced type of hypoglycemia, resemble an extreme shock reaction. Symptoms include:
  • cold and pale skin
  • numbness around the mouth
  • apprehension
  • heart palpitations
  • emotional outbursts
  • hand tremors
  • mental cloudiness
  • dilated pupils
  • sweating
  • fainting
Mild attacks, however, are more common in reactive hypoglycemia and are characterized by extreme tiredness. Patients first lose their alertness, then their muscle strength and coordination. Thinking grows fuzzy, and finally the patient becomes so tired that he or she becomes "zombie-like," awake but not functioning. Sometimes the patient will actually fall asleep. Unplanned naps are typical of the chronic hypoglycemic patient, particularly following meals.
Additional symptoms of reactive hypoglycemia include headaches, double vision, staggering or inability to walk, a craving for salt and/or sweets, abdominal distress, premenstrual tension, chronic colitis, allergies, ringing in the ears, unusual patterns in the frequency of urination, skin eruptions and inflammations, pain in the neck and shoulder muscles, memory problems, and sudden and excessive sweating.
Unfortunately, a number of these symptoms mimic those of other conditions. For example, the depression, insomnia, irritability, lack of concentration, crying spells, phobias, forgetfulness, confusion, unsocial behavior, and suicidal tendencies commonly seen in nervous system and psychiatric disorders also may be hypoglycemic symptoms. It is very important that anyone with symptoms that may suggest reactive hypoglycemia see a doctor.
Because all of its possible symptoms are not likely to be seen in any one person at a specific time, diagnosing hypoglycemia can be difficult. One or more of its many symptoms may be due to another illness. Symptoms may persist in a variety of forms for long periods of time. Symptoms also can change over time within the same person. Some of the factors that can influence symptoms include physical or mental activities, physical or mental state, the amount of time passed since the last meal, the amount and quality of sleep, and exercise patterns.


Drug-induced hypoglycemia

Once diabetes is diagnosed, the patient then monitors his or her blood sugar level with a portable machine called a glucometer. The diabetic places a small blood sample on a test strip that the machine can read. If the test reveals that the blood sugar level is too low, the diabetic can make a correction by eating or drinking an additional carbohydrate.

Reactive hypoglycemia

Reactive hypoglycemia only can be diagnosed by a doctor. Symptoms usually improve after the patient has gone on an appropriate diet. Reactive hypoglycemia was diagnosed more frequently 10-20 years ago than today. Studies have shown that most people suffering from its symptoms test normal for blood sugar, leading many doctors to suggest that actual cases of reactive hypoglycemia are quite rare. Some doctors think that people with hypoglycemic symptoms may be particularly sensitive to the body's normal postmeal release of the hormone epinephrine, or are actually suffering from some other physical or mental problem. Other doctors believe reactive hypoglycemia actually is the early onset of diabetes that occurs after a number of years. There continues to be disagreement about the cause of reactive hypoglycemia.
A common test to diagnose hypoglycemia is the extended oral glucose tolerance test. Following an overnight fast, a concentrated solution of glucose is drunk and blood samples are taken hourly for five to six hours. Though this test remains helpful in early identification of diabetes, its use in diagnosing chronic reactive hypoglycemia has lost favor because it can trigger hypoglycemic symptoms in people with otherwise normal glucose readings. Some doctors now recommend that blood sugar be tested at the actual time a person experiences hypoglycemic symptoms.


Treatment of the immediate symptoms of hypoglycemia can include eating sugar. For example, a patient can eat a piece of candy, drink milk, or drink fruit juice. Glucose tablets can be used by patients, especially those who are diabetic. Effective treatment of hypoglycemia over time requires the patient to follow a modified diet. Patients usually are encouraged to eat small, but frequent, meals throughout the day, avoiding excess simple sugars (including alcohol), fats, and fruit drinks. Those patients with severe hypoglycemia may require fast-acting glucagon injections that can stabilize their blood sugar within approximately 15 minutes.

Alternative treatment

A holistic approach to reactive hypoglycemia is based on the belief that a number of factors may create the condition. Among them are heredity, the effects of other illnesses, emotional stress, too much or too little exercise, bad lighting, poor diet, and environmental pollution. Therefore, a number of alternative methods have been proposed as useful in treating the condition. Homeopathy, acupuncture, and applied kinesiology, for example, have been used, as have herbal remedies. One of the herbal remedies commonly suggested for hypoglycemia is a decoction (an extract made by boiling) of gentian (Gentiana lutea). It should be drunk warm 15-30 minutes before a meal. Gentian is believed to help stimulate the endocrine (hormone-producing) glands.
In addition to the dietary modifications recommended above, people with hypoglycemia may benefit from supplementing their diet with chromium, which is believed to help improve blood sugar levels. Chromium is found in whole grain breads and cereals, cheese, molasses, lean meats, and brewer's yeast. Hypoglycemics should avoid alcohol, caffeine, and cigarette smoke, since these substances can cause significant swings in blood sugar levels.


Drug-induced hypoglycemia

Preventing hypoglycemic insulin reactions in diabetics requires taking glucose readings through frequent blood sampling. Insulin then can be regulated based on those readings. Continuous glucose monitoring sensors have been developed to help diabetics remain more aware of possible hypoglycemic episodes. These monitors even can check for episodes while the patient sleeps, when many will experience severe hypoglycemia but not know it. Those who don't pay attention to severe hypoglycemia events or who have had previous severe hypoglycemia are the most likely to have future severe hypoglycemia. An audible alert can let the patient know immediately that he or she needs to take care of his or her blood sugar level. Continuous monitoring has proved particularly helpful in pediatric patients with Type 1 diabetes.
Maintaining proper diet also is a factor. Programmable insulin pumps implanted under the skin have proven useful in reducing the incidence of hypoglycemic episodes for insulin-dependent diabetics. As of late 1997, clinical studies continue to seek additional ways to control diabetes and drug-induced hypoglycemia. Tests of a substance called pramlintide indicate that it may help improve glycemic control in diabetics.

Reactive hypoglycemia

The onset of reactive hypoglycemia can be avoided or at least delayed by following the same kind of diet used to control it. While not as restrictive as the diet diabetics must follow to keep tight control over their disease, it is quite similar.
There are a variety of diet recommendations for the reactive hypoglycemic. Patients should:
  • avoiding overeating
  • never skipping breakfast
  • including protein in all meals and snacks, preferably from sources low in fat, such as the white meat of chicken or turkey, most fish, soy products, or skim milk
  • restricting intake of fats (particularly saturated fats, such as animal fats), and avoiding refined sugars and processed foods
  • being aware of the differences between some vegetables, such as potatoes and carrots. These vegetables have a higher sugar content than others (like squash and broccoli). Patients should be aware of these differences and note any reactions they have to them.
  • being aware of differences found in grain products. White flour is a carbohydrate that is rapidly absorbed into the bloodstream, while oats take much longer to break down in the body.
  • keeping a "food diary." Until the diet is stabilized, a patient should note what and how much he/she eats and drinks at every meal. If symptoms appear following a meal or snack, patients should note them and look for patterns.
  • eat fresh fruits, but restrict the amount they eat at one time. Patients should remember to eat a source of protein whenever they eat high sources of carbohydrate like fruit. Apples make particularly good snacks because, of all fruits, the carbohydrate in apples is digested most slowly.
  • following a diet that is high in fiber. Fruit is a good source of fiber, as are oatmeal and oat bran. Fiber slows the buildup of sugar in the blood during digestion.
A doctor can recommend a proper diet, and there are many cookbooks available for diabetics. Recipes found in such books are equally effective in helping to control hypoglycemia.


Like diabetes, there is no cure for reactive hypoglycemia, only ways to control it. While some chronic cases will continue through life (rarely is there complete remission of the condition), others will develop into type II (age onset) diabetes. Hypoglycemia appears to have a higher-than-average incidence in families where there has been a history of hypoglycemia or diabetes among their members, but whether hypoglycemia is a controllable warning of oncoming diabetes has not yet been determined by clinical research.
A condition known as hypoglycemia unawareness can develop in those who do not control their blood glucose, particularly in people with Type 1 diabetes. These people may lose notice of the automatic warning symptoms of hypoglycemia that normally occur as their bodies become so used to frequent periods of hypoglycemia. It is not a permanent event, but can be treated by careful avoidance of hypoglycemia for about two weeks.



Ruggiero, Roberta. The Do's and Don'ts of Low Blood Sugar. Hollywood, FL: Frederick Fell Publishers.


Brauker, James, et al. "Use of Continuous Glucose Monitoring Alerts to Better Predict, Prevent and Treat Postprandial Hyperglycemia." Diabetes June 2003: 90-91.
Gertzman, Jerilyn, et al. "Severity of Hypoglycemia and Hypoglycemia Unawareness Are Associated with the Extent of Unsuspected Nocturnal Hypoglycemia." Diabetes June 2003:146-151.
Kumar, Rajeev, and Miles Fisher. "Impaired Hypoglycemia Awareness: Are we Aware?" Diabetes and Primary Care Summer 2004: 33-38.
Ludvigsson, Johnny, and Ragnar Hanas. "Continuous Subcutaneous Glucose Monitoring Improved Metabolic Control in Pediatric Patients With Type 1 Diabetes: A Controlled Crossover Study." Pediatrics May 2003: 933-936.


Hypoglycemia Association, Inc. 18008 New Hampshire Ave., PO Box 165, Ashton, MD 20861-0165.
National Hypoglycemia Association, Inc. PO Box 120, Ridgewood, NJ 07451. (201) 670-1189.

Key terms

Adrenal glands — Two organs that sit atop the kidneys; these glands make and release hormones such as epinephrine.
Epinephrine — Also called adrenalin, a secretion of the adrenal glands (along with norepinephrine) that helps the liver release glucose and limits the release of insulin. Norepinephrine is both a hormone and a neurotransmitter, a substance that transmits nerve signals.
Fructose — A type of natural sugar found in many fruits, vegetables, and in honey.
Glucagon — A hormone produced in the pancreas that raises the level of glucose in the blood. An injectable form of glucagon, which can be bought in a drug store, is sometimes used to treat insulin shock.
Postprandial — After eating or after a meal.
Gale Encyclopedia of Medicine. Copyright 2008 The Gale Group, Inc. All rights reserved.


an abnormally low level of glucose in the blood, usually because glucose has been either removed at an excessive rate or secreted into the blood at a decreased rate. Overproduction of insulin by the islets of Langerhans or an overdose of exogenous insulin can lead to increased utilization of glucose, causing it to be removed from the blood at an accelerated rate. Some large tumors of the retroperitoneal area and tumors of the islets of Langerhans can increase the production of insulin and result in rapid removal of glucose from the blood. Because the liver is the source of most of the glucose entering the blood while a person is fasting, damage to the liver cells can result in impaired ability to convert glycogen into glucose. If secretion of the adrenocortical hormones, especially the glucocorticoids, is deficient, the protein precursors of glucose are not available and the blood glucose level drops as the liver's glycogen supply is depleted.
Symptoms. Hypoglycemia may be tolerated by normal persons for brief periods of time without symptoms; however, if the blood sugar level remains very low for a long time, symptoms of cerebral dysfunction develop. These include mental confusion, hallucinations, convulsions, and eventually deep coma as the nervous system is deprived of the glucose needed for its normal metabolic activities. Other symptoms are a result of a greatly increased secretion of epinephrine, a normal response to hypoglycemia. The patient then experiences increased pulse rate, tachycardia, a rise in blood pressure, sweating, and anxiety.
Treatment. An acute episode requires careful assessment, with prompt measurement of capillary blood glucose levels. The American Diabetes Association notes than when symptoms occur, corrective action can often be taken by eating carbohydrates. The patient who is unconscious or who is experiencing seizures related to low blood sugar should receive an intravenous bolus of dextrose (50 per cent solution). A family member should be taught to administer glucagon to patients who may experience hypoglycemia and lose consciousness at home. Glucagon can also be administered to the hospitalized patient in an emergency situation when a vein cannot be located.

Specific treatment depends on the primary cause of hypoglycemia. If hyperinsulinism is due to a tumor or hyperplasia of the islands of Langerhans, surgical intervention is necessary to remove this cause of hypoglycemia. The large sarcomas of the retroperitoneal or mediastinal areas that cause hyperinsulinism also must be treated surgically.

Reactive or postprandial hypoglycemia, thought to be a precursor of diabetes mellitus, is a form of low blood sugar that develops rather suddenly several hours after ingestion of a high carbohydrate meal. It is characterized by a blood sugar level of 50 mg/100 ml or less, and symptoms of palpitations, sweating, anxiety, hunger, and tremulousness. The usual treatment for this form of chronic hypoglycemia involves dietary changes that are aimed at avoiding extremes in blood glucose level and maintaining an adequate level of glucose in the blood at all times. The diet is high in protein and fat and low in carbohydrate content and is given in frequent, small feedings during the day and before retiring. This regimen avoids extreme fluctuations in blood glucose concentration by restricting carbohydrate intake, and supplies adequate precursors of glycogen through the protein intake.
Miller-Keane Encyclopedia and Dictionary of Medicine, Nursing, and Allied Health, Seventh Edition. © 2003 by Saunders, an imprint of Elsevier, Inc. All rights reserved.


Symptoms resulting from low blood glucose (normal glucose range 60-100 mg/dL [3.3-5.6 mmol/L]), which are either autonomic or neuroglycopenic. Autonomic symptoms include sweating, trembling, feelings of warmth, anxiety, and nausea. Neuroglycopenic symptoms include feelings of dizziness, confusion, tiredness, difficulty speaking, headache, and inability to concentrate.
Synonym(s): glucopenia
Farlex Partner Medical Dictionary © Farlex 2012


An abnormally low level of glucose in the blood.
The American Heritage® Medical Dictionary Copyright © 2007, 2004 by Houghton Mifflin Company. Published by Houghton Mifflin Company. All rights reserved.


Endocrinology A ↓ in blood glucose, often linked to systemic disease Clinical Headache, tremors, sweating, pallor, syncope, ↓ concentration, coma; fasting hypoglycemia occurs in endocrinopathies–eg, hypopituitarism, Addison's disease, adrenogenital syndrome, islet cell tumors, factitious insulin ingestion, non-pancreatic neoplasms–eg, retroperitoneal sarcoma producing ectopic insulin, hepatic disease, glycogen storage disease; postprandial hypoglycemia may be functional and idiopathic–associated with preclinical DM, gastrectomy, or drug-related–eg, sulfonylureas, oral hypoglycemics–eg, chlorpropamide, tolbutamide, tolazamide, acetohexamide, alcohol, aspirin, phenformin, insulin. See Drug-induced hypoglycemia, Glucose tolerance test, Reactive hypoglycemia.
McGraw-Hill Concise Dictionary of Modern Medicine. © 2002 by The McGraw-Hill Companies, Inc.


An abnormally low concentration of glucose in the circulating blood.
Synonym(s): hypoglycaemia.
Medical Dictionary for the Health Professions and Nursing © Farlex 2012


Symptoms resulting from low blood glucose (normal glucose range 60-100 mg/dL [3.3-5.6 mmol/L]), which are either autonomic or neuroglycopenic.
Synonym(s): glucopenia, hypoglycaemia.
Medical Dictionary for the Dental Professions © Farlex 2012

Patient discussion about hypoglycemia

Q. What is hypoglycemia? What exactly is hypoglycemia and why is it so dangerous?

A. Hypoglycemia is the sudden decrease in blood glucose levels, to an amount where the body experiences signs and symptoms such as confusion, fast heart rate, altered consciousness state and even fainting. This is usually a result of medications taken for diabetes. In most cases, hypoglycemia is treated with sugary drinks or food. In severe cases, an injection of glucagon (a hormone with the opposite effects of insulin) or an intravenous infusion of dextrose is used for treatment, but usually only if the person is unconscious.

Q. I have Type II Diabetes, but have regular problems with low blood sugar levels. What should I do? I am an over 60 female who has been diagnosed with Type II Diabetes. I was originally on Metformin, but my doctor discontinued it because I was having severe low blood sugar levels a lot (as low as 40). I have heard that putting me on insulin might help, but I don't see how since I have more low than high levels. Anyone have any suggestions or information about what I can do? (I do follow diabetic eating with proper food and frequent small meals, but that doesn't seem to help.)

A. i'm not sure about this but maybe because of your sensitivity to Metformin they want to move to insulin shots because they want accuracy. but as all it sounds a bit strange, cause most of the times they save that as a last resort. there's probably something else that's missing here...you asked them why insulin shots?

More discussions about hypoglycemia
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References in periodicals archive ?
Continuous glucose monitoring reveals delayed nocturnal hypoglycemia after intermittent high-intensity exercise in nontrained patients with type 1 diabetes.
Frequency of severe hypoglycemia in patients with type I diabetes with impaired awareness of hypoglycemia.
Less nocturnal hypoglycemia for insulin degludec vs.
(46.) Rosenstock L Vico M, Wei L, Salsali A, List JE Effects of dapagliflozin, a SGLT2 inhibitor, on HbAlc, body weight, and hypoglycemia risk in patients with type 2 diabetes inadequately controlled on pioglitazone monotherapy.
Improving epinephrine responses in hypoglycemia unawareness with real-time continuous glucose monitoring in adolescents with type 1 diabetes.
Long-term effect of an education program (HYPOS) on the incidence of severe hypoglycemia in patients with type 1 diabetes.
* Compare the risk of hypoglycemia among glucose-lowering agents.
* Identify patient risk factors and behaviors that increase the risk of hypoglycemia.
* Describe techniques physicians may use to identify patients at risk for hypoglycemia.