Hypoglycemia

Definition
Hypoglycemia is defined as low blood sugar, typically less than 50 mg/dl. Depending on when you last ate, normal blood sugar is about 70 mg/dl to 110 mg/dl. While fasting, for example, your blood sugar level may fall to less than 50 or 60 mg/dl. However, consistent blood sugar levels at 45 mg/dl or less are more likely to indicate a medical condition.

Understanding blood sugar
Carbohydrates in your diet, such as sugars and starches, are important sources of glucose (sugar). Your brain needs a steady source of glucose to function properly, and glucose helps your body meet its energy needs. When glucose levels are too low, the brain and nervous system become deprived of their primary energy source. A lack of glucose to the brain, which triggers a hormonal response, may cause a variety of symptoms.
To make sure a steady amount of glucose is available, the body has natural mechanisms in place to deal with blood sugar fluctuations. When blood sugar is low, for example, adrenaline is released to restore and maintain blood sugar levels by converting fat and glycogen (a substance produced by the liver and stored both in the liver and in the muscles) into glucose. Certain hormones, including cortisol and growth hormones, also raise blood sugar levels. When you fast, a hormone called glucagon helps your body maintain blood sugar levels by converting glycogen into glucose. Insulin, a hormone produced by the pancreas, lowers high blood sugar after you eat. Reduced amounts of insulin are found in the blood when you have hypoglycemia.


Causes/associated factors
Hypoglycemia can be caused by a variety of factors. The condition is most common in people who have diabetes (a condition in which glucose cannot work properly because of a problem with carbohydrate metabolism).
If you have diabetes, hypoglycemia may develop when:

a dose of insulin or oral antidiabetic agent is too large
you skip or miss a meal and have already taken your medications or insulin
there is extended or vigorous physical activity
you take other medications, such as aspirin, quinine, beta blockers, haloperidol or pentamidine
infrequently, when you have another illness
you drink alcohol in excess
If you don't have diabetes, hypoglycemia may be related to:

liver disease
kidney diseases
early pregnancy
early diabetes or prediabetes changes
a history of stomach surgery
dietary habits, such as regular alcohol or caffeine intake with minimal eating
certain weight loss diets
Addison's disease (a disease in which the adrenal glands -- glands that produce a range of hormones -- fail to produce enough steroid hormones)
pituitary problems
rarely, an insulin-producing tumor in the islet cells of the pancreas (called an insulinoma)
other rare tumors
Sometimes, hereditary disorders cause hypoglycemia. These disorders include fructose intolerance (a rare condition usually seen in children) or a rare genetic disorder called galactosemia (a condition that impairs the body's ability to metabolize a form of sugar called galactose). Rarely, there may also be hereditary hormone or enzyme deficiencies.

Normally, growth hormones antagonize the action of insulin on muscle and fat cells. Children who have a growth hormone deficiency may develop hypoglycemia because the deficiency can lead to increased insulin sensitivity. The condition is typically resolved with appropriate treatment.


Types of hypoglycemia
There are two types of hypoglycemia:
Reactive hypoglycemia usually develops suddenly, within two to five hours after eating foods high in glucose (or earlier if part of your stomach has been removed). This type of hypoglycemia typically lasts about 15 to 20 minutes. Reactive hypoglycemia may develop in people who are obese or have a family history of diabetes. Sometimes reactive hypoglycemia develops for no known reason.

Fasting hypoglycemia may develop if it's been more than five hours since your last meal. This type of hypoglycemia is more likely when you have a hormonally active tumor in your pancreas or lack endocrine hormones.

Signs/symptoms
Low blood sugar levels don't always trigger symptoms. Depending on the person, symptoms may develop at different blood sugar levels and range from mild to severe. Symptoms may include any of the following:
weakness
trembling
dizziness
pale skin
heavy, cold perspiration
nervousness or irritability
hunger
heart palpitations or rapid heartbeat
tingling sensation in the hands or feet
fatigue or drowsiness
nausea
headache
mental sluggishness, difficulty concentrating or confusion
blurred vision
poor coordination
unusual behavior patterns such as stubbornness or uncooperativeness (may resemble a state of intoxication)
seizures, particularly in children
eventually, stupor or unconsciousness

Diagnosis
The doctor will review your medical history and current symptoms and do a physical exam. Blood tests may be done to screen for blood sugar abnormalities, especially if you're experiencing symptoms. The doctor may also suggest a 72-hour supervised fasting test, which is done in the hospital. At home, the doctor may also ask you to check your blood sugar levels when you have symptoms. Because the symptoms of hypoglycemia can occur with many other clinical conditions, additional tests may be done to help diagnose any underlying medical problems. For example, the doctor may also order lab tests to determine insulin production and levels of C-peptide, a substance released into the blood by the pancreas in the same amounts as insulin.
For people who don't have diabetes, a diagnosis of hypoglycemia is based on three factors called Whipple's triad:

symptoms of hypoglycemia
a low glucose level (45 mg/dl or less for women, or 55 mg/dl or less for men) that accompanies the symptoms
improvement of symptoms when sugar is eaten

Treatment
Treatment is based on your health status and the severity of your symptoms.
If you're unconscious or unable to swallow, 911 emergency services are needed immediately. In the hospital, you'll be given intravenous dextrose (a form of sugar). Your blood sugar levels and general condition will be monitored closely, and you'll be treated for any underlying conditions. If you have unstable or severe diabetes, your family members should learn how to give glucagon shots (an injectable hormone). Glucagon can quickly reduce further symptoms, as well as the possible complications associated with extremely low or prolonged hypoglycemia.

If you're alert, get sugar into your system. Try 4 to 6 ounces of orange juice, apple juice, a soft drink containing sugar, two to three sugar cubes, five to six pieces of hard candy, or a tablespoon of honey or grape jelly. If your symptoms don't disappear within 10 to 15 minutes, have a second helping of sugar. You may also want to have a snack containing protein to prevent further symptoms from developing.

Long-term management of hypoglycemia may involve a combination of factors, including medication changes or dosage adjustments. Any underlying conditions will be treated and monitored. Your doctor may also suggest dietary management, such as decreasing your intake of sweets and simple sugars and eating more complex carbohydrates (which are absorbed more slowly) with adequate amounts of protein. You may also need to eat frequent small meals throughout the day and have a bedtime snack.


Complications
People who have type 1 diabetes, a specific type of diabetes, are the most susceptible to severe low blood glucose reactions, although anyone using an insulin sensitizer or insulin secretagogue (oral medicines used by people who have type 2 diabetes) can have these reactions. Eventually, a condition called hypoglycemia unawareness may develop. With this condition, you'll have difficulty identifying the onset of a hypoglycemic reaction. Severe hypoglycemia can lead to unconsciousness, coma and neurological damage (involving the brain or nervous system). Without treatment, severe hypoglycemia can be fatal.

Pregnancy-specific information
You may notice more pronounced symptoms of hypoglycemia when you're pregnant. For reasons not clearly understood, pregnancy lowers fasting blood sugar levels. To avoid hypoglycemia, consult your health care provider about healthy eating during pregnancy.

Senior-specific information
The symptoms of hypoglycemia are often similar to those of other medical conditions common among older adults. If you notice any symptoms that may indicate hypoglycemia, consult your doctor.

Prevention
If you have a history of hypoglycemia, always wear or carry medical identification that describes your condition and the emergency medical treatment you may need. To help prevent hypoglycemic episodes, avoid skipping meals, going for long periods without food, and exercising excessively.
If you have diabetes, follow your diet and treatment plan and maintain a blood sugar level that's within the target range recommended by your doctor. Inform your doctor of any lifestyle or health changes so that your treatment plan can be adjusted as needed. For help planning meals and managing your diet, consult a registered dietitian.

If you have reactive hypoglycemia unrelated to other medical conditions, follow your prescribed diet or a healthy meal plan. Include a variety of foods, such as whole grains, fruits and vegetables. Eat small, frequent meals or snacks throughout the day with a snack at bedtime. Avoid mealtime delays, alcohol, caffeine, simple carbohydrates (sweets such as cookies or candy), and foods or beverages that trigger your symptoms. A registered dietitian can help you develop an individualized diet plan and avoid foods that may lead to hypoglycemic episodes.

Consult your doctor if your condition doesn't respond to self-care measures or you experience frequent episodes of hypoglycemia, anxiety or depression.