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 the treatment of diabetes. However, a 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.
Immediate treatment of hypoglycemia involves quick steps to get your blood sugar level back into a normal range — about 70 to 100 milligrams per deciliter or mg/dL (3.9 to 5.6 millimoles per liter or mmol/L) — either with high-sugar foods or medications. Long-term treatment requires identifying and treating the underlying cause of hypoglycemia.
Your body needs a steady supply of sugar (glucose) in order to function properly. If glucose levels become too low, as occurs with hypoglycemia, it can have these effects on your brain:
Hypoglycemia may also cause these other signs and symptoms:
These signs and symptoms aren't specific to hypoglycemia. There may be other causes. An intravenous blood sample to test your blood sugar level at the time of these signs and symptoms is the only way to know for sure that hypoglycemia is the cause.
When to see a doctor
Hypoglycemia occurs when your 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 your body normally regulates blood sugar production, absorption and storage.
Blood sugar regulation
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 level 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 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. To prevent this from happening, it's likely that your doctor will work with you to find the optimum dosage that fits your regular eating and activity habits.
Possible causes, without diabetes
Hypoglycemia after meals
If you ignore the symptoms of hypoglycemia too long, you may lose consciousness. That's because your brain needs glucose to function properly.
Recognize the signs and symptoms of hypoglycemia early because untreated hypoglycemia can lead to:
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.
Preparing for your appointment
If you have diabetes and you have symptoms of hypoglycemia, call the doctor who normally helps manage your condition. If you haven't been diagnosed with diabetes, make an appointment with your primary care provider.
Here's some information to help you get ready for your appointment and know what to expect from your doctor.
What you can do
Questions to ask your doctor if you have diabetes include:
Questions to ask if you haven't been diagnosed with diabetes include:
In addition to the questions that you've prepared to ask your doctor, don't hesitate to ask questions during your appointment.
What to expect from your doctor
If you have diabetes, your doctor also may ask a number of detailed questions about your diabetes management. It will help to come to your appointment with a recent log of blood sugar test results, medication names and schedules and any changes you've noticed in the frequency or severity of diabetes-related symptoms.
Tests and diagnosis
Your doctor will use three criteria — often referred to as Whipple's triad — to diagnose hypoglycemia. Whipple's triad includes the following factors:
In addition, your doctor will likely conduct a physical examination and review your medical history.
Treatments and drugs
Treatment of hypoglycemia involves:
Immediate initial treatment
Treatment of the underlying condition
Last Updated: 2012-02-22
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