In general testing is done to determine the cause of an illness or to determine what disease is present. The correct treatment is possible only if correct diagnosis is mode.

Doctor must decide how frequently a person must be tested for diabetes. It may depend upon patient’s age and number of risk factors present in him. As if the patient is 45 years old or more than that, then he/she must be tested for diabetes every three years. But if the person in younger than 45 but have one or more risk factors, then he should be also regularly tested.

Normally a urine analysis may be used to look for glucose and ketones produced by the break down of fat and muscle. But a urine test alone does not diagnose diabetes because there are certain other things also which can cause sugar to appear in urine.

The following blood glucose tests are used to diagnose diabetes:

1. THE FASTING BLOOD GLUCOSE (SUGAR) TEST:

It is the best way to diagnose diabetes. It is very comfortable and easy to perform. The person is asked to fast overnight (at least 8 hours), then a sample of blood is drawn and is sent to laboratory for analysis. It the fasting blood glucose level comes out to be less than 100 milligrams per deciliter (mg/dl) then the person is believed to be normal. If the fasting blood glucose level lies between 100 and 126 milligrams per deciliter (mg/dl) then they are referred to as Impaired Fasting Glucose or Pre-diabetes. This level is considered to be risk factor for Type 2 Diabetes and its complications. Every year 1.5 of people who shows Impaired Fasting Glucose, infect develop diabetes in coming days. But if patient exercise and loose weight then impaired fasting glucose levels return to normal.

If the overnight fasting blood glucose level is more than 126 mg/dl on two different tests on different days, them the person is said to be suffering from diabetes.

2. RANDON (NON-FASTING) BLOOD GLUCOSE TEST:

It is also a better way to diagnose diabetes. When classic symptoms like increased thirst, urination and fatigue are present, them random blood samples (taken shortly after eating or drinking) are used to test for diabetes. If the blood glucose level is higher than 200 mg/dl, then the patient is said to be diabetic, but it must be reconfirmed by fasting blood glucose test on the another day or by an oral Glucose Tolerance Test.

3. ORAL GLUCOSE TOLERANCE TEST (OGTT):

It is not used routinely nowadays, but still it serves as a gold standard for diagnosing diabetes. This test measures the rate at which sugar is removed from the blood. It is more commonly used for diagnosing Gestational Diabetes.

Instructions given to the patients before Oral Glucose Tolerance Test are as follow:-

TEST PROCEDURE

First of all fasting blood glucose is tested. Then the person is given 75 gm of glucose but the pregnant woman is given 100 gms of glucose. Normally, the glucose is a sweet tasting liquid that the person drinks. The blood samples are taken at particular intervals to measure the blood glucose. In general, the blood glucose level is measured five times over a period of 3 hours. Person who does not suffer from diabetes, shows rise in the blood glucose levels, which fall down quickly but in person suffering from diabetes the blood glucose level rise higher than normal but does not come down quickly.

Individuals with fasting value of plasma glucose higher than 140mg/dl and 2 hours value after 75 gm oral glucose higher than 200 mg/dl are labeled as diabetics. But the individuals with fasting and 2 hours plasma glucose value between 140 and 200mg/dl are considered to have impaired fasting glucose. These patients are kept under observation for repeating the test later. However, during pregnancy, a case of impaired fasting glucose is treated as Diabetic. The patient on whom OGTT is performed may complain of nausea, vomiting etc.

4 . OTHER TESTS:

i) Glycosylated haemoglobin Test:

During this test, the glycosylated haemoglobin (a minor haemoglobin component present in normal persons) is measured. This is because the non-enzymatic glycosylation of haemoglobin takes place over 120 days, life span of red blood cells. Therefore, this test gives and estimates of diabetes control for the coming 6-10 weeks.

ii) Intravenous GTT:

This test is performed in persons who have intestinal malabsorption.

iii) Extended GTT:

In this the oral Glucose Tolerance Test is extended to 3-4 hours for appearance of symptoms of hyperglycaemia.