The Importance of Fasting before a Diabetes Test

Diabetes can be described as a disorder of insulin in the body. Either due to insufficient or diminishing production of insulin from the pancreas OR due to vascular resistance to the effects of insulin OR both. In any case, the function of blood glucose regulation (a process mediated by the hormone insulin) is significantly impaired. A diabetic patient will therefore be unable to regulate his blood glucose without the aid of anti-diabetes tablets, insulin injection or diet. Some will need all three interventions at once whilst others will progress from diet control to tablets and then to insulin injections. To determine the dose of tablet to give, or the dose of insulin to give; the physician must have a way of testing the patient’s glucose level. The diabetic patient may also use these blood glucose levels (or diabetes test) to determine how well they are managing their condition.

Why is blood glucose so important?

Glucose is a very important energy source in the body. If it is too low, then key organs of the body such as the brain will be starved of energy. In extreme cases this will lead to coma and death. If the blood glucose level is too high, then patient might start producing excessive urine (polyurea), feeling hungry and thirsty. A characteristic smell of Ketone may be present. In extreme case damage to kidney, irregular heart beat and coma may occur. It is therefore important to keep blood glucose within the normal levels.

Diabetes test are useful ways of determining the blood glucose level. These tests can be performed at anytime. There are two times times which are commonly quoted: Random blood glucose and Fasting blood glucose. As the name implies, a random blood glucose tests are done at anytime and is very useful to do when a diabetic patient is feeling unwell all of a sudden. This is to enable him indentify if the sudden feeling of unwell has anything to do with his blood glucose. The fasting glucose however, provides a more accurate picture of the blood glucose and is used by physicians for diagnosing patients.

The fasting blood glucose:

The fasting blood glucose is the blood glucose level from a patients who has not eaten or drank anything (except water) for at least 8 hours prior to the sampling time. This will eliminate the effect of food on the blood glucose level. Most of us eat three times a day, roughly 8 hours apart. It takes about 8 hours (or less) after food (depending on type) for a normal body to deal with all the energy obtained from that meal. Generally speaking, the blood glucose after 8 hours of food should return to the normal range (usually described as less than 99mg/dl). However, in diabetes patients, this will be higher because of the insulin problems described above. This is why physicians use this test as a tool for diagnosing diabetes.

Fasting blood glucose or Fasting plasma glucose ( )

99mg/dl or below === NORMAL


200mg/dl and above === DIABETES

If you don’t fast as described above prior to a diabetes test, there is a good chance that you may end up with the wrong diagnosis. Diabetes is a serious condition and getting the diagnosis right first time is crucial.