Hypoglycemia
(Low Blood Sugar)

What is the medical definition of hypoglycemia?

Hypoglycemia (low blood sugar) is a commonly perceived problem. In actuality, while some or many of the symptoms may be present, it is rarely confirmed or documented. 

What causes low blood sugar without diabetes?

The presence of true, documented hypoglycemia in the absence of diabetes treatment must be evaluated comprehensively by an endocrinologist. Hypoglycemia most often affects those at the extremes of age, such as infants and the elderly, but may happen at any age. Generally, hypoglycemia is defined as a serum glucose level (the amount of sugar or glucose in your blood) below 70 mg/dL.

As a medical problem, hypoglycemia is diagnosed by the presence of three key features (known as Whipple's triad). Whipple's triad is:

1. symptoms consistent with hypoglycemia,
2. a low plasma glucose concentration, and
3. relief of symptoms after the plasma glucose level is raised.

What are the symptoms of non-diabetic hypoglycemia?

Symptoms of hypoglycemia typically appear at levels below 60 mg/dL. Some people may feel symptoms above this level. Levels below 50 mg/dL affect brain function.

The body regulates its glucose level—the primary source of energy for the brain, muscles, and other essential cells - by the actions of different hormones. These hormones include insulin (which lowers the blood sugar level) and other chemicals which raise blood sugar (such as glucagon, growth hormone, and epinephrine).

• Both insulin and glucagon are manufactured in the pancreas, an organ near the stomach which assists the digestive tract. Special cells in the pancreas, called beta cells, make insulin. Alpha cells in the pancreas make glucagon.
• The role of insulin is to help in the absorption of glucose from the blood by causing it to be stored in the liver or be transported into other tissues of the body (for metabolism or storage).
• Glucagon increases the amount of glucose in the blood by breaking down stored glucose (starch, called glycogen) and releasing it from the liver into the bloodstream.
• Insulin and glucagon are usually correctly balanced if the liver and pancreas are functioning normally.

Traditionally considered a stress hormone, epinephrine (or adrenalin) is made in the adrenal gland and in certain cells in the central nervous system. Epinephrine also elevates blood glucose levels by making glucose available for the body during a time of stress. When this mechanism is not working properly, hypoglycemia can result. Other hormones also help in raising the level of blood glucose, like cortisol made by the adrenal gland and growth hormone made by the pituitary gland.

Common causes of low blood sugar include the following:

• Overmedication with insulin or antidiabetic pills (for example, sulfonylurea drugs)
• Use of medications such as beta blockers, pentamidine, and sulfamethoxazole and trimethoprim (Bactrim, Septra)
• Use of alcohol
• Missed meals
• Reactive hypoglycemia is the result of the delayed insulin release after a meal has been absorbed and occurs 4-6 hours after eating.
• Severe infection
• Cancer causing poor oral intake or cancer involving the liver
• Adrenal insufficiency
• Kidney failure
• Liver failure
• Congenital, genetic defects in the regulation of insulin release (congenital hyperinsulinism)
• Congenital conditions associated with increased insulin release (infant born to a diabetic mother, birth trauma, reduced oxygen delivery during birth, major birth stress, Beckwith-Wiedemann syndrome, and rarer genetic conditions)
• Insulinoma or insulin-producing tumor
• Other tumors like hepatoma, mesothelioma, and fibrosarcoma, which may produce insulin-like factors

What follows are expansions on the points noted above and should be incorporated within those points (such as cancer, diabetes drugs, organ failures).

• Most cases of hypoglycemia in adults happen in people with diabetes mellitus. Diabetes has two forms, type 1 (loss of all insulin production) and type 2 (inadequate insulin production due to resistance to the actions of insulin). People with type 1 diabetes must take insulin to control their glucose level; if they skip meals or have a decreased appetite without changing their insulin dose, they may develop hypoglycemia. Insulin is also used to treat some people with type 2 diabetes.
• If a person with type 1 diabetes accidentally takes too much insulin, or a person with type 2 diabetes accidentally takes too much of their oral medications or insulin, he or she may develop hypoglycemia. Even when a diabetic patient takes medications correctly, improper meals, odd mealtimes, or excessive exercise may result in hypoglycemia.
• Often a person who has more than one medical problem may become confused about how much of a certain medication they should take, or their medications may interact to cause hypoglycemia.
• Hypoglycemia also may occur in people with cancer, which often causes loss of appetite. Many such people skip meals because they are not hungry or because chemotherapy causes foods to taste differently. To prevent this, people on chemotherapy should be encouraged by their doctors and loved ones to try to stay on special diets and take medications to keep them from feeling sick. If this does not work, special medications to help with appetite are available.
• Adrenal insufficiency results from diseases that impair the adrenal glands, which are located above the kidneys. These small structures make certain hormones and substances, mainly cortisol and epinephrine, which also help elevate glucose in addition to their other functions. If these substances are not made, low blood pressure, hypoglycemia, or both can result.
• The pituitary gland makes growth hormone, which also helps to maintain the balance of glucose. Deficiency of growth hormone causes hypoglycemia, especially in young infants and children.
• Kidney failure causes hypoglycemia in three separate ways. The kidneys help to generate new glucose from amino acids (called gluconeogenesis). Gluconeogenesis is impaired in kidney failure. Also, insulin circulates for a longer period of time and is cleared slowly when kidney function is poor. The third important reason is that kidney failure reduces the appetite and consequently, oral intake of food.
• The liver stores glucose in a form called glycogen. In the presence of liver failure, the abilities of the liver to generate new glucose and to release glucose are impaired.
• Insulin-producing tumors of the pancreas (called insulinomas) cause hypoglycemia by releasing inappropriately high amounts of insulin. Certain tumors of the liver called hepatomas or other tumors such as fibrosarcomas and mesotheliomas can also cause hypoglycemia by producing insulin-like factors.

Epinephrine is among the major hormones released during hypoglycemia. Epinephrine causes the majority of the early symptoms of hypoglycemia.

Common symptoms of hypoglycemia include the following:

• trembling,
• clammy skin,
• palpitations (pounding or fast heart beats),
• anxiety,
• sweating,
• hunger, and
• irritability.

When the brain remains deprived of glucose, a later set of symptoms follows:

• difficulty in thinking,
• confusion,
• headache,
• seizures, and
• coma.

Ultimately, after significant coma or loss of consciousness, death can occur.

It is important to realize that with chronic or repeated hypoglycemia, the body does not respond as vigorously, so any hypoglycemic individual may display mild symptoms, or even experience no appreciable symptoms. Again, documentation of the blood glucose level is essential to confirm the diagnosis, with further testing to establish the specific cause if not known.

When to call the doctor

If you suspect a person has hypoglycemia, immediate action must be taken to increase the blood sugar level. Otherwise, organs begin to malfunction (for example, the hypoglycemic brain may develop seizures). You can always give sugar at least once to a diabetic patient with symptoms of low blood sugar. If their blood sugar is already high, then the small amount given will not do any harm. If the blood sugar is low, giving it can be lifesaving.

• If the person is awake and alert, give orange juice (or any available juice). Water with added sugar also works (a couple teaspoons or sugar packets per 4 ounces).
• Other useful therapies include cake icing, glucose gel, glucose tablets, or instant glucose (a paste-like substance that has concentrated glucose). People with diabetes should routinely carry such a remedy for potential emergency use (by themselves or a companion).
• If the person is confused, call emergency services (911 in most situations). If a medical cabinet is available, find a glucagon kit. This counter-regulatory hormone can be injected to reverse hypoglycemia quickly. A glucagon injection will work if the body's stores of glycogen are adequate, as is the case with most patients taking insulin.
• When the ambulance arrives, medical personnel will ask you some questions. If you know that the person has diabetes, tell them. Also, let them know that you suspect that the person is hypoglycemic, and report any treatments which have been administered so far. They will have instant glucose, glucagon, and concentrated glucose which they can administer after establishing an intravenous access.
• If the person looks very sleepy, and you are unable to awaken them, place them on their side with the left side down to prevent them from choking or vomiting.
• If you or someone you love has diabetes, ask your doctor to refer you to a diabetes education class and learn more about the disease and hypoglycemia.

Please ask your doctor about the following:

• How to recognize hypoglycemia
• How to treat hypoglycemia that occurs in you or a family member or coworkers
• How to prevent hypoglycemia
• Whom to contact in an emergency
• What emergency supplies to carry with you to treat hypoglycemia
• Educational material regarding hypoglycemia

The doctor will assess the adequacy of the patient's medications. Changes in eating habits or in their medication regimen may be recommended. A blood test known as the hemoglobin A1c may be performed to assess the patient's blood sugar control over the past three-month period.

Kidney function and liver function may be checked. If low sugar is unexplained, then further tests are indicated to assess adrenal gland function and to rule out insulinoma or other problems as causes of hypoglycemia.

A glucose monitor is available for people to check their own blood sugars in the comfort and privacy of their own home.

• This entails poking yourself on a fingertip or the forearm to get a drop of blood.
• The blood is transferred to a special strip of paper that is placed into the glucose meter (called a glucometer) which analyzes the blood. The meter gives a numeric reading that corresponds to the blood glucose level.

If you find someone who has the symptoms of hypoglycemia, look for clues that explain the symptoms.

• If the person has a recently disposed needle, you can presume that a change in their level of consciousness may be due to hypoglycemia. He or she may have accidentally taken too much insulin.
• If the person is awake enough to drink something, you can give them a cup of orange juice, cake icing, or water containing table sugar. If hypoglycemia was the cause of their confusion, they will improve within 5-10 minutes.

In the hospital or at your doctor's office, treatment may require intravenous glucose or a glucagon injection (given into the muscle).

The best medication is glucose, given orally as cake icing, hard candy (not chocolate), a liquid containing table sugar, or intravenously as dextrose-containing solutions. Adrenal insufficiency is treated by giving hydrocortisone (as tablets or intramuscular injection, pending definitive medical therapy). Children with growth hormone deficiency are treated with daily growth hormone injections.

The physician may prescribe specific medications, like diazoxide (Proglycem) or streptozotocin (Zanosar), if the low sugar is refractory or recurrent. These drugs work by suppressing insulin release from the pancreatic beta cells.

Hypoglycemia may be caused by a tumor in the pancreas (called insulinoma) or abnormal cells in non-pancreatic tumors (non-islet cell tumor hypoglycemia, or NICTH). These tumors may be benign (no metastases) or malignant (spreading metastases to other tissues). Surgery is the best treatment for an insulinoma. Special tests by the endocrinologist may assist the surgeon in removing less pancreatic tissue, reducing the risk of diabetes after surgery. If the tumor is malignant or cannot be operated on, certain medications may be able to suppress insulin release from the diseased pancreatic beta cells.

Consult a physician if symptoms of hypoglycemia recur. Additional tests may be performed by the doctor. Avoid self-medication or self-adjustment of medications.

Hypoglycemia prevention is done best through proper use of diabetic medications and proper nutrition and mealtimes.

• Carefully choose the right size of syringe for the insulin injection.
• Never consume more than the prescribed dose of medications (oral hypoglycemic agents). For example, if the patient's blood sugar level is high, do not take two pills if only one pill was prescribed. Such doubling or similarly excessive use of medication can cause serious hypoglycemia.
• Eat on time and never miss meals.
• Keep track of what is eaten in relation to how much exercise the person gets. If the person has diabetes have diabetes, vigorous exercise without reasonable food intake can cause hypoglycemia. However, do not avoid exercise simply due to the potential risk of hypoglycemia. The benefits of exercise far outweigh the small risk of serious hypoglycemia.
• Avoid excessive consumption of alcohol.
• Be sure to eat adequate amounts of food.