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Hypoglycemia, also called low blood sugar, occurs when your blood glucose
(blood sugar) level drops too low to provide enough energy for your body's
activities. In adults or children older than 10 years, hypoglycemia is
uncommon except as a side effect of diabetes treatment, but it can result
from other medications or diseases, hormone or enzyme deficiencies, or
Glucose, a form of sugar, is an important fuel for your body. Carbohydrates
are the main dietary sources of glucose. Rice, potatoes, bread, tortillas,
cereal, milk, fruit, and sweets are all carbohydrate-rich foods.
After a meal, glucose molecules are absorbed into your bloodstream and
carried to the cells, where they are used for energy. Insulin, a hormone
produced by your pancreas, helps glucose enter cells. If you take in more
glucose than your body needs at the time, your body stores the extra glucose
in your liver and muscles in a form called glycogen. Your body can use
the stored glucose whenever it is needed for energy between meals. Extra
glucose can also be converted to fat and stored in fat cells.
When blood glucose begins to fall, glucagon, another hormone produced
by the pancreas, signals the liver to break down glycogen and release glucose,
causing blood glucose levels to rise toward a normal level. If you have
diabetes, this glucagon response to hypoglycemia may be impaired, making
it harder for your glucose levels to return to the normal range.
Symptoms of hypoglycemia include
- nervousness and shakiness
- dizziness or light-headedness
- difficulty speaking
- feeling anxious or weak
- Hypoglycemia can also happen while you are sleeping.
- cry out or have nightmares
- find that your pajamas or sheets are damp from perspiration
- feel tired, irritable, or confused when you wake up
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Hypoglycemia can occur in people with diabetes who take certain medications
to keep their blood glucose levels in control. Usually hypoglycemia is
mild and can easily be treated by eating or drinking something with carbohydrate.
But left untreated, hypoglycemia can lead to loss of consciousness. Although
hypoglycemia can happen suddenly, it can usually be treated quickly, bringing
your blood glucose level back to normal.
In people taking certain blood-glucose lowering medications, blood glucose
can fall too low for a number of reasons:
- meals or snacks that are too small, delayed, or skipped
- excessive doses of insulin or some diabetes medications, including
sulfonylureas and meglitinides (Alpha-glucosidase inhibitors, biguanides,
and thiazolidinediones alone should not cause hypoglycemia but can when
used with other diabetes medicines.)
- increased activity or exercise
- excessive drinking of alcohol
Your diabetes treatment plan is designed to match your medication dosage
and schedule to your usual meals and activities. If you take insulin but
then skip a meal, the insulin will still lower your blood glucose, but it
will not find the food it is designed to break down. This mismatch might
result in hypoglycemia.
To help prevent hypoglycemia, you should keep in mind several things:
Your diabetes medications. Some medications can cause hypoglycemia. Ask your
health care provider if yours can. Also, always take medications and insulin
in the recommended doses and at the recommended times.
What to Ask Your Doctor About Your Diabetes Medications
Could my diabetes medication cause hypoglycemia?
- When should I take my diabetes medication?
- How much should I take?
- Should I keep taking my diabetes medication if I am sick?
- Should I adjust my medication before exercise?
Your meal plan. Meet with a registered dietitian and agree on a meal plan
that fits your preferences and lifestyle. Do your best to follow this meal
plan most of the time. Eat regular meals, have enough food at each meal,
and try not to skip meals or snacks.
Your daily activity. Talk to your health care team about whether you should
have a snack or adjust your medication before sports or exercise. If you
know that you will be more active than usual or will be doing something
that is not part of your normal routine--shoveling snow, for example--consider
having a snack first.
Alcoholic beverages. Drinking, especially on an empty stomach, can cause
hypoglycemia, even a day or two later. If you drink an alcoholic beverage,
always have a snack or meal at the same time.
Your diabetes management plan. Intensive diabetes management--keeping your
blood glucose as close to the normal range as possible to prevent long-term
complications--can increase the risk of hypoglycemia. If your goal is tight
control, talk to your health care team about ways to prevent hypoglycemia
and how best to treat it if it does occur.
|Normal and target blood glucose ranges (mg/dL)
|Normal blood glucose levels in people who do not have diabetes
|Upon waking (fasting)
||70 to 110
||70 to 140
|Target blood glucose levels in people who have diabetes
||90 to 130
|1 to 2 hours after the start of a meal
||less than 180
|Hypoglycemia (low blood glucose)
||70 or below
If you think your blood glucose is too low, use a blood glucose meter to
check your level. If it is 70 mg/dL or below, have one of these "quick
fix" foods right away to raise your blood glucose:
- 2 or 3 glucose tablets
- 1/2 cup (4 ounces) of any fruit juice
- 1/2 cup (4 ounces) of a regular (not diet) soft drink
- 1 cup (8 ounces) of milk
- 5 or 6 pieces of hard candy
- 1 or 2 teaspoons of sugar or honey
After 15 minutes, check your blood glucose again to make sure that it is
no longer too low. If it is still too low, have another serving. Repeat these
steps until your blood glucose is at least 70. Then, if it will be an hour
or more before your next meal, have a snack.
If you take insulin or a diabetes medication that can cause hypoglycemia,
always carry one of the quick-fix foods with you. Wearing a medical identification
bracelet or necklace is also a good idea.
Exercise can also cause hypoglycemia. Check your blood glucose before you
Severe hypoglycemia can cause you to lose consciousness. In these extreme
cases when you lose consciousness and cannot eat, glucagon can be injected
to quickly raise your blood glucose level. Ask your health care provider
if having a glucagon kit at home and at work is appropriate for you. This
is particularly important if you have type 1 diabetes. Your family, friends,
and co-workers will need to be taught how to give you a glucagon injection
in an emergency.
Prevention of hypoglycemia while you are driving a vehicle is especially
important. Checking blood glucose frequently and snacking as needed to keep
your blood glucose above 70 mg/dL will help prevent accidents.
Hypoglycemia and Diabetes: Doing Your Part
Signs and symptoms of hypoglycemia can vary from person to person. Get to
know your own signs and describe them to your friends and family so they
will be able to help you. If your child has diabetes, tell school staff
about hypoglycemia and how to treat it.
If you experience hypoglycemia several times a week, call your health care
provider. You may need a change in your treatment plan: less medication or
a different medication, a new schedule for your insulin shots or medication,
a different meal plan, or a new exercise plan.
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Two types of hypoglycemia can occur in people who do not have diabetes:
reactive (postprandial, or after meals) and fasting (postabsorptive). Reactive
hypoglycemia is not usually related to any underlying disease; fasting hypoglycemia
Symptoms of both types resemble the symptoms that people with diabetes and
hypoglycemia experience: hunger, nervousness, perspiration, shakiness,
dizziness, light-headedness, sleepiness, confusion, difficulty speaking,
and feeling anxious or weak.
If you are diagnosed with hypoglycemia, your doctor will try to find the
cause by using laboratory tests to measure blood glucose, insulin, and other
chemicals that play a part in the body's use of energy.
In reactive hypoglycemia, symptoms appear within 4 hours after you eat a
To diagnose reactive hypoglycemia, your doctor may
ask you about signs and symptoms
test your blood glucose while you are having symptoms (The doctor will take
a blood sample from your arm and send it to a laboratory for analysis. A
personal blood glucose monitor cannot be used to diagnose reactive hypoglycemia.)
check to see whether your symptoms ease after your blood glucose returns
to 70 or above (after eating or drinking)
A blood glucose level of less than 70 mg/dL at the time of symptoms and relief
after eating will confirm the diagnosis.
The oral glucose tolerance test is no longer used to diagnose hypoglycemia;
experts now know that the test can actually trigger hypoglycemic symptoms.
Causes and Treatment
The causes of most cases of reactive hypoglycemia are still open to debate.
Some researchers suggest that certain people may be more sensitive to the
body's normal release of the hormone epinephrine, which causes many of
the symptoms of hypoglycemia. Others believe that deficiencies in glucagon
secretion might lead to hypoglycemia.
A few causes of reactive hypoglycemia are certain, but they are uncommon.
Gastric (stomach) surgery, for instance, can cause hypoglycemia because of
the rapid passage of food into the small intestine. Also, rare enzyme deficiencies
diagnosed early in life, such as hereditary fructose intolerance, may cause
To relieve reactive hypoglycemia, some health professionals recommend taking
the following steps:
eat small meals and snacks about every 3 hours
eat a variety of foods, including meat, poultry, fish, or nonmeat sources
of protein; starchy foods such as whole-grain bread, rice, and potatoes;
fruits; vegetables; and dairy products
choose high-fiber foods
avoid or limit foods high in sugar, especially on an empty stomach
Your doctor can refer you to a registered dietitian for personalized meal
planning advice. Although some health professionals recommend a diet high
in protein and low in carbohydrates, studies have not proven the effectiveness
of this kind of diet for reactive hypoglycemia.
Fasting hypoglycemia is diagnosed from a blood sample that shows a blood
glucose level of less than 50 mg/dL after an overnight fast, between meals,
or after exercise.
Causes and Treatment
Causes include certain medications, alcohol, critical illnesses, hormonal
deficiencies, some kinds of tumors, and certain conditions occurring in
infancy and childhood.
Medications, including some used to treat diabetes, are the most common cause
of hypoglycemia. Other medications that can cause hypoglycemia include
salicylates, including aspirin, when taken in large doses
sulfa medicines, which are used to treat infections
pentamidine, which treats a very serious kind of pneumonia
quinine, which is used to treat malaria
If using any of these medications causes your blood glucose to drop, your
doctor may advise you to stop using the drug or change the dosage.
Drinking, especially binge drinking, can cause hypoglycemia because your
body's breakdown of alcohol interferes with your liver's efforts to raise
blood glucose. Hypoglycemia caused by excessive drinking can be very serious
and even fatal.
Some illnesses that affect the liver, heart, or kidneys can cause hypoglycemia.
Sepsis (overwhelming infection) and starvation are other causes of hypoglycemia.
In these cases, treatment targets the underlying cause.
Hormonal deficiencies may cause hypoglycemia in very young children, but
usually not in adults. Shortages of cortisol, growth hormone, glucagon,
or epinephrine can lead to fasting hypoglycemia. Laboratory tests for hormone
levels will determine a diagnosis and treatment. Hormone replacement therapy
may be advised.
Insulinomas, insulin-producing tumors, can cause hypoglycemia by raising
your insulin levels too high in relation to your blood glucose level. These
tumors are very rare and do not normally spread to other parts of the body.
Laboratory tests can pinpoint the exact cause. Treatment involves both
short-term steps to correct the hypoglycemia and medical or surgical measures
to remove the tumor.
Conditions Occurring in Infancy and Childhood
Children rarely develop hypoglycemia. If they do, causes may include
Brief intolerance to fasting, often in conjunction with an illness that
disturbs regular eating patterns. Children usually outgrow this tendency
by age 10.
Hyperinsulinism, which is the excessive production of insulin. This condition
can result in transient neonatal hypoglycemia, which is common in infants
of mothers with diabetes. Persistent hyperinsulinism in infants or children
is a complex disorder that requires prompt evaluation and treatment by a
Enzyme deficiencies that affect carbohydrate metabolism. These deficiencies
can interfere with the body's ability to process natural sugars, such as
fructose and galactose, glycogen, or other metabolites.
Hormonal deficiencies such as lack of pituitary or adrenal hormones.
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If you think your blood glucose is low, check it and treat the problem right
To treat hypoglycemia, have a serving of a quick-fix food, wait 15 minutes,
and check your blood glucose. Repeat the treatment until your blood glucose
is above 70.
Keep quick-fix foods in the car, at work--anywhere you spend time.
Be careful when you are driving. Check your blood glucose frequently and
snack as needed to keep your level above 70 mg/dL.
Hypoglycemia Unrelated to Diabetes
In reactive hypoglycemia, symptoms occur within 4 hours of eating. People
with this condition are usually advised to follow a healthy eating plan recommended
by a registered dietitian.
Fasting hypoglycemia can be caused by certain medications, critical illnesses,
hereditary enzyme or hormonal deficiencies, and some kinds of tumors. Treatment
targets the underlying problem.
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Juvenile Diabetes Research
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