Understanding The Numbers

Fasting Blood Sugar and Other Glucose Tests

By Allan Wu

Fasting blood sugar or FBS is a test for the levels of glucose in blood. Glucose is the major monosaccharide in blood. Its measurement is vital to the diagnosis of diabetes mellitus. Fasting, because the patient has to fast for 8-12 hours before testing. Fasting is crucial to come up with reliable laboratory results and consequently – diagnosis.

How is Fasting Blood Sugar performed?

1. When the test is ordered, the patient should contact the health worker responsible in the collection of the specimen.

2. Proper instructions are given. Instructions may vary, if there are other tests simultaneously done with FBS. Examples are: If it is done with triglyceride test, fasting would be 12-14 hours. If electrolyte is performed, water may not be permitted.

3. Fasting usually starts after the evening meal. 7 pm to 7 am. Nothing is eaten; not even candy, coffee, tea or any beverage.

4. Before 7 am, the patient should already be in the laboratory.

5. Blood then is extracted and properly labeled and encoded.

6. The patient can eat after the blood extraction.

7. The fasting hours should not be shortened or prolonged.

Other tests that can be performed with glucose in the diagnosis of Diabetes Mellitus (DM) are:

1. 2 -hour post prandial test (2-HPPT)

This is the most sensitive parameter in diagnosing diabetes mellitus. It is because two hours after a meal (post prandially), glucose levels in normal persons will go back to normal.

Normal blood glucose levels in adult:

Orthotoulidine method = 60-110 mg/dL

Nelson-Somogyi method = 80-120 mg/dL

2. Oral Glucose Tolerance Test (OGTT)

The patient ingests a glucose load/challenge or solution. Then timed specimens are collected at 30 minutes or one-hour intervals. The results are compared to standard results for normal patients.

3. Intravenous Glucose Tolerance Test (IGTT)

This is the same as OGTT. The difference is that the glucose load is injected intravenously. Persons who have gastrointestinal problems employ IGTT. Obtained results are interpreted just like OGTT.

4. HbA1C test (Hemoglobin A1C).

This test is a measure of the patient’s compliance to his drug treatment. If the patient is dutifully taking in his medicine, the obtained result would be normal. If the patient is not complying with his medications, then the result is elevated.

It is good that people become aware of these different tests, so that they would be able to monitor their glucose levels or that of diabetic relatives and friends.

Allan enjoys writing up on a variety of subjects. Other than the above topic, he also likes to set up sites on different topics. Do check out his new site which covers useful information on women’s perfume.

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