2- Several different types of blood glucose tests
are used
Introduction
A blood glucose test measures
the amount of a type of sugar, called glucose, in
your blood. Glucose comes from carbohydrate foods.
It is the main source of energy used by the body. Insulin
is a hormone
that helps your body use and control the amount of glucose in your blood. Insulin
is produced in the pancreas
and released into the blood when the amount of glucose in the blood rises.
Normally,
your blood glucose levels increase slightly after you eat. This increase causes
your pancreas to release insulin so that your blood glucose levels do not get
too high. Blood glucose levels that remain high over time can damage your eyes,
kidneys, nerves, and blood vessels.
Several different types of blood glucose tests
are used.
Fasting blood sugar (FBS)
The "gold
standard" for diagnosing diabetes is an elevated blood sugar level after an overnight fast at least 8 hours (not eating anything after
midnight).It often is the first test done to check for diabetes. A value above 140 mg/dl on at least two
occasions typically means a person has diabetes. Normal people have fasting
sugar levels that generally run between 70-110 mg/dl.
2-hour postprandial blood
sugar (2-hour PC)
Measures blood
glucose exactly 2 hours after you eat a meal.
Random blood sugar (RBS )
Measures
blood glucose regardless of when you last ate. Several random measurements may
be taken throughout the day. Random testing is useful because glucose levels in
healthy people do not vary widely throughout the day. Blood glucose
levels that vary widely may indicate a problem. This test is also called a
casual blood glucose test.
Oral glucose tolerance
test(OGTT)
An oral glucose tolerance test is one that can be
performed in a lab. The person being tested starts the test in a fasting state
(having no food or drink except water for at least 8 hours but not greater than
16 hours). An initial blood sugar is drawn and then the person is given 75
grams of glucose, (or 100 grams for pregnant women). The person then has their blood
tested again 30 minutes, 1 hour, 2 hours and 3 hours after drinking the high glucose
drink.
For the test to give reliable results, you must be
in good health (not have any other illnesses, not even a cold). Also, you
should be normally active (for example, not lying down or confined to a bed
like a patient in a hospital) and taking no medicines that could affect your
blood glucose. The morning of the test, you should not smoke or drink coffee.
During the test, you need to lie or sit quietly.
The oral glucose tolerance test is conducted by
measuring blood glucose levels five times over a period of 3 hours.
In a person without diabetes, the glucose levels in the blood rise following drinking the glucose drink, but then fall quickly back to normal
(because insulin is produced in response to the glucose , and the insulin has a
normal effect of lowing blood glucose .) In a diabetic, glucose levels rise higher than normal after drinking
the glucose drink and come down to
normal levels much slower (insulin is either not produced, or it is produced
but the cells of the body do not respond to it) .
