FBS TEST
The fasting blood sugar test (FBS) sometimes called a fasting plasma glucose test it measures the amount of glucose (sugar) in the blood when you have not had anything to eat or drink for several hours, this test is normally done in the mornings.
A fasting blood sugar (FBS) level is one of the tests used to diagnose diabetes mellitus (the others being the oral glucose tolerance test and the A1C level). In a person with symptoms of osmotic diuresis and an elevated fasting blood sugar level, the diagnosis of diabetes mellitus is usually made.
The fasting blood sugar is determined by taking a sample of venous blood after at least eight hours of fasting. The sugar level is then evaluated in the blood sample.
Why is this test done?
Rationale for using fasting blood sugar;
The most common use of this test is to check for diabetes. The blood glucose level is usually maintained in a range of 3.2 - 6.4 mmol/L. Between meals, and even during an overnight fast, that level is still maintained, even in the absence of food intake. The body does this by converting glycogen to glucose and when necessary, fats to glucose through carbohydrate metabolism. These two methods of producing glucose maintain a normal glucose level during fasting.
The ability to convert glycogen to glucose presupposes that the body converts glucose to glycogen when the glucose level is high, that is, after a meal. This process requires insulin which brings the glucose level back to normal a few hours after a meal.
In a diabetic patient, the lack of insulin keeps the glucose level elevated even after fasting overnight. When the blood sugar level reaches a critical level, symptoms of osmotic d
Glucose testing can be used to diagnose or indicate certain medical conditions.
High blood sugar may mean:
- Gestational diabetes. This is a temporary form of diabetes that appears during pregnancy, and with glucose-controlling medication or insulin symptoms can be improved.
- Type 1 and type 2 diabetes or prediabetes. Regular glucose tests can help manage or maintain conditions if diagnosed with diabetes. Type 1, is commonly seen in children or teenagers whose bodies are not producing enough insulin. Type 2 diabetes, is typically seen in adults who are overweight. The insulin in these bodies are either not working normally, or there is not enough being produced.
- pancreatic cancer
- pancreatitis
- underactive thyroid
Low blood sugar may indicate:
- An overuse of Insulin
- Starvation
- An underactive thyroid
- Addison's disease
- Insulinoma
- A kidney disease
How does one prepare for this test?
The simplest way to check for diabetes is to check blood sugar before you've had anything to eat or drink in the morning. In most cases you will fast overnight, eating nothing and drinking nothing but water after the evening meal and in the morning before the blood is drawn.
It is best to have the blood checked after the usual sleeping time i.e. after at least 6 hours of sleep and at the beginning of the active day. The patient is asked not to eat or drink anything except water before blood is drawn for the test. Certain medicines may have to be avoided before the test because they might affect the test result. The patient must inform the doctor about any medicines, herbs, or supplements that he/she is taking. Patients must not stop taking any regular medicines without first consulting with the doctor.
How is the test conducted?
The healthcare provider may poke a finger with a lancet and fill a small tube with the blood. Or a small amount of blood may be taken from an arm with a needle. The blood is sent to a lab.
Having this test will take just a few minutes.
Testing methods
Some tests that can be performed at home are used in blood glucose monitoring for illnesses that have already been diagnosed medically. This allows for these illnesses to be maintained via medication and meal timing.
Some of the home testing methods include:
- Finger prick type of glucose meter. (Will need to prick self with lancet to apply on glucose meter)
- Continuous glucose monitor (The CGM monitors the glucose levels approximately every 5 minutes).
Laboratory tests are often used to diagnose illnesses and such methods include:
- Fasting blood sugar (FBS) fasting plasma glucose (FPG): 10–16 hours after eating
- Glucose tolerance test: continuous testing
- Postprandial glucose test (PC): 2 hours after eating
- Random glucose test
Some of the laboratory tests do not measure glucose levels directly from body fluids or tissues but they still indicate elevated blood sugar levels. Instead, such tests measure the levels of glycated hemoglobin, other glycated proteins from the blood.
Understanding the FBS Test result
The normal range for fasting blood sugar is 3.2 to 6.4mmol/L, it varies from laboratory to laboratory.
A fasting blood sugar level elevated above 6.4mmol/L may imply impaired fasting glucose or prediabetes. A level of 7.0mmol/L or higher could mean the patient has diabetes. The test should be repeated at another time to confirm the result.
A patient could have hyperglycemia (blood sugar level that is higher than normal) if:
- He has prediabetes, a condition that can become diabetes.
- He has diabetes.
- He has previously been diagnosed of diabetes and Patient has not been taking insulin or diabetes medicine, or the diabetes medicine is not adequately controlling the diabetes.
- Patient has not been following a diabetic diet.
- Patient has kidney or liver disease.
- The pancreas is inflamed.
- The body is severely stressed from an illness, infection, or injury.
- Patient is taking medicine, such as steroids (Prednisone), which can raise blood sugar.
A patient may have hypoglycemia (blood sugar level may be lower than normal) if:
- He has diabetes and:
- The dose of insulin or other medicine used to control the diabetes is too high.
- He took his medicine for diabetes but then did not eat.
- His thyroid, pituitary, or adrenal glands are not working normally.
- He has liver disease.
- He has problems with absorbing food.
- He is not getting the needednutrients from his diet.
What if the test result is not normal?
Test results are only one part of a larger picture that takes into account a person’s medical history and current health. Sometimes a test needs to be repeated to confirm the first result. Patients must inquire from their healthcare provider about their test results and ask questions about:
Whether more tests will be necessary
The kind of treatment that might be needed
What lifestyle, diet, or other changes might be needed.
