Hypoglycemia is a condition characterized by an abnormally low level of blood sugar (glucose), your body’s main energy source.
Hypoglycemia is commonly associated with diabetes. However, a wide variety of conditions, many of them rare, can cause low blood sugar in people without diabetes. Like fever, hypoglycemia isn’t a disease itself — it’s an indicator of a health problem.
Treatment of hypoglycemia involves short-term steps to get your blood sugar level back into a normal range and long-term steps by your doctor to identify and treat the underlying cause of hypoglycemia.
Your brain needs a steady supply of sugar (glucose), for it neither stores nor manufactures its own energy supply. If glucose levels become too low, as occurs with hypoglycemia, it can have these effects on your brain:
- Confusion, abnormal behavior or both, such as the inability to complete routine tasks
- Visual disturbances, such as double vision and blurred vision
- Seizures, though uncommon
- Loss of consciousness, though uncommon
Hypoglycemia may also cause these other signs and symptoms:
- Heart palpitations
These signs and symptoms aren’t specific to hypoglycemia. There may be other causes. The only way to know for sure that hypoglycemia is the cause is by having your blood sugar level measured at the time of these symptoms.
Hypoglycemia occurs when your blood sugar (glucose) level falls too low. There are a number of 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 your body normally regulates blood sugar production, absorption and storage.
Blood sugar regulation
During digestion, your 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 your body. Glucose is absorbed directly into your bloodstream after you eat, but it can’t enter the cells of most of your tissues without the help of insulin — a hormone secreted by your pancreas.
When the level of glucose in your blood rises, it signals certain cells (beta cells) in your pancreas, located behind your stomach, to release insulin. The insulin, in turn, unlocks your cells so that glucose can enter and provide the fuel your cells need to function properly. Any extra glucose is stored in your liver and muscles in the form of glycogen. This process lowers the amount of glucose in your bloodstream and prevents it from reaching dangerously high levels. As your blood sugar level returns to normal, so does the secretion of insulin from your pancreas.
If you haven’t eaten for several hours and your blood sugar level drops, another hormone from your pancreas called glucagon signals your liver to break down the stored glycogen and release glucose back into your bloodstream. This keeps your blood sugar level within a normal range until you eat again.
Aside from your liver breaking down glycogen into glucose, your body also has the ability to manufacture glucose in a process called gluconeogenesis. This process occurs primarily in your liver, but also in your kidneys, and makes use of various substances that are precursors to glucose.
Possible causes, with diabetes
If you have diabetes, the effects of insulin on your body are drastically diminished, either because your pancreas doesn’t produce enough of it (type 1 diabetes) or because your cells are less responsive to it (type 2 diabetes). As a result, glucose tends to build up in your 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 you take too much insulin relative to the amount of glucose in your bloodstream, it can cause your blood sugar level to drop too low, resulting in hypoglycemia. Hypoglycemia may also result if, after taking your diabetes medication, you don’t eat as much as usual (ingesting less glucose) or you exercise more (using up more glucose) than you normally would. Your doctor usually works with you to find the optimum dosage that fits your regular eating and activity habits to prevent this from happening.
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 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.
- Excessive alcohol consumption. Drinking heavily without eating can block your liver from releasing stored glucose into your bloodstream, causing hypoglycemia.
- Some critical illnesses. Severe illnesses of the liver, such as drug-induced hepatitis, can cause hypoglycemia. Disorders of the kidney, which can keep your 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 your body needs in gluconeogenesis, causing hypoglycemia.
- Tumors. 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. Or, the tumors themselves may use up too much glucose. Enlargement of beta cells of the pancreas that produce insulin (nesidioblastosis) may result in excessive insulin release, causing hypoglycemia. People who’ve undergone gastric bypass surgery are at risk of this condition.
- Endocrine 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
Most hypoglycemia occurs when you haven’t eaten (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 is called reactive or postprandial hypoglycemia.
To diagnose hypoglycemia, your doctor will use Whipple’s triad, a diagnostic approach named after the American surgeon Allen Whipple. Whipple’s triad includes the following factors:
- Signs and symptoms of hypoglycemia. You may not exhibit signs and symptoms of hypoglycemia during your initial visit with your doctor. In this case, your doctor may have you fast overnight. This will allow hypoglycemic symptoms to occur so that he or she can make a diagnosis. It’s also possible that you’ll need to undergo an extended fast in a hospital setting. Or, if your symptoms occur after a meal, your doctor will want to test your glucose levels after a meal.
- Documentation of low blood glucose when the signs and symptoms occur. Your doctor will draw a sample of your blood to be analyzed in the laboratory.
- Disappearance of the signs and symptoms. The third part of the diagnostic triad involves whether your signs and symptoms go away when blood glucose levels are raised.
You’ll likely need a physical examination and a review of your medical history with your doctor. He or she will want to determine what medications you use, whether you drink alcohol excessively and whether you have a critical illness. This will help your doctor confirm whether you have hypoglycemia and determine the likely cause.
If you ignore the symptoms of hypoglycemia too long, you may lose consciousness. That’s because your brain needs glucose to function. Recognize the signs and symptoms of hypoglycemia early because untreated, hypoglycemia can lead to seizures, loss of consciousness and even death.
On the other hand, if you have diabetes be careful not to overtreat your low blood sugar. If you do, you may cause your blood sugar level to rise too high. This, too, can be dangerous and may cause damage to your nerves, blood vessels and various organs.
Treatment of hypoglycemia involves two basic approaches:
- Immediate initial treatment to raise your blood sugar level
- Treatment of the underlying condition that’s causing your hypoglycemia, to prevent it from recurring
The initial treatment depends on your symptoms. Early symptoms can usually be treated by consuming sugar, such as eating candy, drinking fruit juice or taking glucose tablets to raise your blood sugar level. If your symptoms are more severe, impairing your ability to take sugar by mouth, you may need intravenous glucose or an injection of glucagon. If you’re prone to severe episodes of hypoglycemia, ask your doctor if a home glucagon kit might be appropriate for you.
Preventing recurrent hypoglycemia requires your doctor to identify the underlying condition and treat it. Depending on the underlying cause, treatment may involve:
- Medications. If a medication is the cause of your hypoglycemia, your doctor will likely suggest changing the medication or adjusting the dosage.
- Tumor treatment. A tumor in your pancreas is usually treated by surgical removal. Nesidioblastosis, enlargement of the pancreatic cells that make insulin, is treated by partial removal of the pancreas.
- If you have diabetes, carefully follow the diabetes management plan you and your doctor have developed.
- If you don’t have diabetes but have recurring episodes of hypoglycemia, eating frequent small meals throughout the day may keep your blood sugar levels from getting too low.
If you have what appear to be symptoms of hypoglycemia, see your doctor. Hypoglycemia, if confirmed, can be an indication of any number of illnesses, all of which can be serious. By seeing your doctor, you can begin the process of having the underlying illness identified and treated.
If you have diabetes and early signs of hypoglycemia don’t improve with eating or taking glucose tablets, seek immediate help. Also, seek emergency help if someone you know who has diabetes or a history of recurring hypoglycemia loses consciousness.