|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 tumors.
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
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
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. You might
- cry out or have nightmares
- find that your pajamas or sheets are damp
- feel tired, irritable, or confused when you
Hypoglycemia: A Side Effect of Diabetes
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.
Causes of Hypoglycemia
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,
- 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
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
- When should I take my diabetes
- How much should I take?
- Should I keep taking my diabetes
medication if I am sick?
- Should I adjust my medication before
- 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
Normal blood glucose levels in people who do
not have diabetes
|Upon waking (fasting)
||70 to 110
||70 to 140
blood glucose levels in people who have
||90 to 130
|1 to 2 hours after the
start of a meal
|Hypoglycemia (low blood
||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
Exercise can also cause hypoglycemia. Check your
blood glucose before you exercise.
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
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.
Hypoglycemia in People Who Do Not Have Diabetes
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 often is.
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 meal.
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 reactive hypoglycemia.
To relieve reactive hypoglycemia, some health
professionals recommend taking the following steps:
- eat small meals and snacks about every 3
- exercise regularly
- 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
- 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
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
- 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
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
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 specialist.
- 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.
Points to Remember
- If you think your blood glucose is low,
check it and treat the problem right away.
- 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
- Fasting hypoglycemia can be caused by
certain medications, critical illnesses,
hereditary enzyme or hormonal deficiencies, and
some kinds of tumors. Treatment targets the