Hypoglycemia is a condition in which the level of blood sugar (glucose) is abnormally low.
It mostly occurs due to treatment of diabetes. It is not a disease on itself but an indicator of a health problem.
Treatment should be provided immediately in order to stabilize the blood glucose levels within the range of 70 - 110 milligrama per deciliter or mg/dL (3.9-6.1 millimoles per liter or ml/L).
Hypoglycemia is caused when the blood sugar (glucose) level falls too low. There are several reasons why this may happen, the most common being a side effect of drugs used for the treatment of diabetes. But to understand how hypoglycemia happens, it helps to know how the body normally regulates blood sugar production, absorption and storage.
Blood sugar regulation
During digestion, the body breaks down carbohydrates from foods — such as bread, rice, pasta, vegetables, fruit and milk products — into various sugar molecules. One of these sugar molecules is glucose, the main energy source for the body. Glucose is absorbed into the bloodstream after eating, but it can't enter the cells of most of the tissues without the help of insulin — a hormone secreted by the pancreas.
When the level of glucose in the blood rises, it signals certain cells (beta cells) in the pancreas to release insulin. The insulin, in turn, unlocks the cells so that glucose can enter and provide the fuel cells need to function properly. Any extra glucose is stored in the liver and muscles in the form of glycogen. This process lowers the level of glucose in the bloodstream and prevents it from reaching dangerously high levels.
As the blood sugar level returns to normal, so does the secretion of insulin from the pancreas. If a person hasn't eaten for several hours and their blood sugar level drops, another hormone from the pancreas called glucagon signals the liver to break down the stored glycogen and release glucose back into the bloodstream. This keeps the blood sugar level within a normal range until he or she eats again.
Aside from the liver breaking down glycogen into glucose, the body also has the ability to manufacture glucose in a process called gluconeogenesis. This process occurs primarily in the liver, but also in the kidneys, and makes use of various substances that are precursors to glucose.
If a person has 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 tends to build up in the bloodstream and may reach dangerously high levels. To correct this problem, a person likely takes insulin or other drugs designed to lower blood sugar levels.
If he or she 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 if, after taking diabetes medication, a person doesn't eat as much as usual (ingesting less glucose) or you exercise more (using up more glucose) than he or she normally would. This can be prevented by the right dosage of insulin or diabetes medication to take that fits regular eating and activity habits.
Possible causes, without diabetes
Hypoglycemia in people without diabetes is much less common.
Causes may include the following:
- Medications: Taking someone else's oral diabetes medication accidentally is a possible cause of hypoglycemia. Other medications may cause hypoglycemia, especially in children or in people with kidney failure. One example is quinine (Qualaquin), which is used to treat malaria. Excessive alcohol consumption. Drinking heavily without eating can block the liver from releasing stored glucose into the bloodstream, causing hypoglycemia.
- Some critical illnesses: Severe illnesses of the liver, such as severe hepatitis, can cause hypoglycemia. Disorders of the kidney, which can keep the body from properly excreting medications, can affect glucose levels due to a buildup of those medications.
- Insulin overproduction: A rare tumor of the pancreas (insulinoma) may cause overproduction of insulin, resulting in hypoglycemia. Other tumors may result in excessive production of insulin-like substances. Enlargement of beta cells of the pancreas that produce insulin (nesidioblastosis) may result in excessive insulin release, causing hypoglycemia.
- Hormone deficiencies: Certain disorders of the adrenal glands and the pituitary gland can result in a deficiency of key hormones that regulate glucose production. Children with these disorders are more prone to hypoglycemia than are adults.
- Hypoglycemia after meals: Hypoglycemia usually occurs when you haven't eaten (when you're in a fasting state), but that's not always the case. Sometimes hypoglycemia occurs after meals because the body produces more insulin than is needed. This type of hypoglycemia, called reactive or postprandial hypoglycemia, may occur in people who have had stomach surgery. It may also occur in people who haven't had this surgery.
Eating frequent small meals throughout the day can help prevent hypoglycemia.
Patients with diabetes should carefully monitor their blood sugar by taking all the required medications.
A continuous glucose monitor (CGM) can also be used for people with hypoglycemia unawareness. This device inserts a tiny wire under the skin that sends the glucose readings to a receiver every 5 minutes. If the blood sugar levels drop too low, the CMG device alerts a patient with an alarm.