a form of sugar, is the body's main fuel. Hypoglycemia, or low blood sugar,
occurs when blood levels of glucose drop too low to fuel the body's activity.
(sugars and starches) are the body's main dietary sources of glucose.
During digestion, the glucose is absorbed into the blood stream (hence
the term "blood sugar"), which carries it to every cell in the body. Unused
glucose is stored in the liver as glycogen.
can occur as a complication of diabetes, as a condition in itself, or
in association with other disorders.
normal range for blood sugar is about 60 mg/dL (milligrams of glucose
per deciliter of blood) to 120 mg/dL, depending on when a person
last ate. In the fasting state, blood sugar can occasionally fall
below 60 mg/dL and even to below 50 mg/dL and not indicate a serious
abnormality or disease. This can be seen in healthy women, particularly
after prolonged fasting. Blood sugar levels below 45 mg/dL are almost
always associated with a serious abnormality.
the Body Control Glucose?
of glucose in the blood is controlled mainly by:
pancreas, a gland in the upper abdomen, produces insulin and glucagon.
The pancreas is dotted with hormone-producing tissue called the islets
of Langerhans, which contain alpha and beta cells. When blood sugar
rises after a meal, the beta cells release insulin. The insulin helps
glucose enter body cells, lowering blood levels of glucose to the
normal range. When blood sugar drops too low, the alpha cells secrete
glucagon. This signals the liver to release stored glycogen and change
it back to glucose, raising blood sugar levels to the normal range.
Muscles also store glycogen that can be converted to glucose.
that influence blood sugar levels are:
(epinephrine and norepinephrine).
Are the Symptoms of Hypoglycemia?
of hypoglycemia may include:
drowsiness, confusion, hunger, and dizziness.
headache, irritability, trembling, sweating, rapid heart beat, and a
cold, clammy feeling are also signs of low blood sugar.
of consciousness and coma (in severe cases)
associated with hypoglycemia are sometimes mistaken for symptoms
caused by conditions not related to blood sugar. For example, unusual
stress and anxiety can cause excess production of catecholamines, resulting
in symptoms similar to those caused by hypoglycemia but having no relation
to blood sugar levels.
common cause of hypoglycemia is as a complication of diabetes. Diabetes
occurs when the body cannot use glucose for fuel because either the pancreas
is not able to make enough insulin or the insulin that is available is not
effective. As a result, glucose builds up in the blood instead of getting
into body cells.
of treatment in diabetes is to lower high blood sugar levels. To do this,
people with diabetes may use insulin or oral drugs, depending on the type
of diabetes they have or the severity of their condition.
occurs most often in people who use insulin to lower their blood sugar.
All people with type 1 diabetes and some people with type 2 diabetes
use insulin. People with type 2 diabetes who take oral drugs called sulfonylureas
are also vulnerable to low blood sugar episodes. People who have diabetes
often refer to hypoglycemia as an "insulin reaction."
of hypoglycemia in diabetic include:
too much medication
or delaying a meal
too little food for the amount of insulin taken
too much alcohol, or any combination of these factors.
Hypoglycemia in Diabetes
with diabetes should consult their health care providers for individual
guidelines on target blood sugar ranges that are best for them. The
lowest safe blood sugar level for an individual varies, depending on
the person's age, medical condition, and ability to sense hypoglycemic
symptoms. A target range that is safe for a young adult with no diabetes
complications, for example, may be too low for a young child or an older
person who may have other medical problems.
they are attuned to the symptoms, people with diabetes can usually recognize
when their blood sugar levels are dropping too low. They can treat the
condition quickly by eating or drinking something with sugar in it such
as candy, juice, or nondiet soda. Taking glucose tablets or gels (available
in drug stores) is another convenient and quick way to treat hypoglycemia.
with type 1 diabetes are most vulnerable to severe insulin reactions,
which can cause loss of consciousness. A few patients with long-standing
insulin-dependent diabetes may develop a condition known as hypoglycemia
unawareness, in which they have difficulty recognizing the symptoms
of low blood sugar.
use in patients with type 1 diabetes, physicians often prescribe an
injectable form of the hormone glucagon. A glucagon injection
(given by another person) quickly eases the symptoms of low blood sugar,
releasing a burst of glucose into the blood.
medical help may be needed if the person does not recover in a few minutes
after treatment for hypoglycemia. A person suffering a severe insulin
reaction may be admitted to the hospital so that blood sugar can be
with diabetes can reduce or prevent episodes of hypoglycemia by monitoring
their blood sugar levels frequently and learning to recognize the symptoms
of low blood sugar and the situations that may trigger it. They should
consult their health care providers for advice about the best way to
treat low blood sugar. Friends and relatives should know about the symptoms
of hypoglycemia and how to treat it in case of emergency.
of hypoglycemia in people with type 1 diabetes may become more common
now that research has shown that carefully controlled blood sugar helps
prevent the complications of diabetes. Keeping blood sugar in a close-to-normal
range requires multiple injections of insulin each day or use of an
insulin pump, frequent testing of blood glucose, a diet and exercise
plan, and guidance from health care professionals.
in Persons without Diabetes
in people who do not have diabetes is far less common than once believed.
periods of strenuous exercise
on beta blocker medications who exercise
can induce hypoglycemia in some children
alcohol can cause blood sugar to drop in some sensitive individuals
has been well documented in chronic alcoholics and binge drinkers. Eating
unripe ackee fruit from Jamaica is a rare cause of low blood sugar.
hypoglycemia in people who do not have diabetes, the doctor looks for
the following three conditions:
complains of symptoms of hypoglycemia
glucose levels are measured while the person is experiencing those
symptoms and found to be 45 mg/dL or less in a woman or 55 mg/dL or
less in a man
are promptly relieved upon ingestion of sugar.
years, the oral glucose tolerance test (OGTT) was used to diagnose hypoglycemia.
Experts now realize that the OGTT can actually trigger hypoglycemic
symptoms in people with no signs of the disorder. For a more accurate
diagnosis, experts now recommend that blood sugar be tested at the same
time a person is experiencing hypoglycemic symptoms.
will also check the patient for health conditions such as diabetes,
obtain a medication history, and assess the degree and severity of the
patient's symptoms. Laboratory tests to measure insulin production and
levels of C-peptide (a substance that the pancreas releases into the
bloodstream in equal amounts to insulin) may be performed.
of reactive hypoglycemia is considered only after other possible causes
of low blood sugar have been ruled out. Reactive hypoglycemia with no
known cause is a condition in which the symptoms of low blood sugar
appear 2 to 5 hours after eating foods high in glucose.
20 years ago, hypoglycemia was a popular diagnosis. However, studies
now show that this condition is actually quite rare. In these studies,
most patients who experienced the symptoms of hypoglycemia after eating
glucose-rich foods consistently had normal levels of blood sugar--above
60 mg/dL. Some researchers have suggested that some people may be extra
sensitive to the body's normal release of the hormone epinephrine after
with symptoms of reactive hypoglycemia unrelated to other medical conditions
or problems are usually advised to follow a healthy eating plan. The
doctor or dietitian may suggest that such a person avoid foods high
in carbohydrates; eat small, frequent meals and snacks throughout the
day; exercise regularly; and eat a variety of foods, including whole
grains, vegetables, and fruits.
Causes of Hypoglycemia
hypoglycemia occurs when the stomach is empty. It usually develops in
the early morning when a person awakens.
enzyme or hormone deficiencies
fructose intolerance is a disorder usually seen in children
in which the body is unable to metabolize the natural sugar fructose.
Attacks of hypoglycemia, marked by seizures, vomiting, and unconsciousness,
are treated by giving glucose and eliminating fructose from the
a rare genetic disorder, hampers the body's ability to process the
sugar galactose. An infant with this disorder may appear normal
at birth, but after a few days or weeks of
drinking milk (which contains galactose), the child may begin to
vomit, lose weight, and develop cataracts. The liver may
fail to release stored glycogen into the blood, triggering hypoglycemia.
Removing milk from the diet is the usual treatment.
hormone deficiency causes increased sensitivity to insulin.
This sensitivity occurs because growth hormone opposes the action
of insulin on muscle and fat cells. For this reason, children with
growth hormone deficiency sometimes suffer from hypoglycemia, which
goes away after treatment.
tumors, which arise in the islet cells of the pancreas, can
cause severe episodes of hypoglycemia.
diagnose these tumors, called insulinomas, a doctor will put the
patient on a 24- to 72-hour fast while measuring blood levels of
glucose, insulin, and proinsulin. High levels of insulin and proinsulin
in the presence of low levels of glucose strongly suggest an insulin-producing
tumor. These tumors are usually benign and can be surgically removed.
cases, some cancers such as breast cancer and adrenal cancer may cause
hypoglycemia through secretion of a hormone called insulin-like growth
factor II. The treatment is removal of the tumor, if possible.
Corner acknowledges the NIDDK
(NIH Publication No. 95-3926) as the primary source for this publication.
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