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Tests for type 2 diabetes

There are several tests that may be arranged for type 2 diabetes. A doctor may recommend these if a person is experiencing symptoms of type 2 diabetes, including increased thirst, frequent urination, and unexplained weight loss.

Fasting blood glucose test

The fasting blood glucose test (FBG) is the preferred method for diagnosing diabetes because it is easy to do and relatively convenient.

How do I prepare for the blood glucose test?

Before taking the blood glucose test, you will not be allowed to eat or drink anything for at least eight hours.

What happens during the blood glucose test?

During a blood glucose test, blood will be drawn and sent to a laboratory for analysis.

What do the results of the blood glucose test mean?

Normal fasting blood plasma glucose is between 4 and 6 millimols per litre or mmol/l for people who do not have diabetes. The standard diagnosis of diabetes is made when two separate blood tests show that your fasting blood glucose level is greater than or equal to 7 mmol/l. If your fasting blood glucose level is between 6 and 7 mmol/l you may have impaired glucose tolerance, also called pre- diabetes. This is not diabetes, but may mean your body is not processing glucose properly.

If you have impaired glucose tolerance, or if you have a normal fasting blood glucose, together with risk factors for diabetes or symptoms of diabetes, your doctor may decide to do a glucose tolerance test (see below) to be sure that you do not have diabetes.

Random blood glucose test for diabetes

The random blood glucose test is another method of diagnosing diabetes. During the test, blood sugar is tested without regard to the time since the person's last meal. You are not required to abstain from eating prior to the test.

A blood glucose level greater than 11.1 mmol/l may indicate diabetes, especially if the test is repeated at a later time and shows similar results.

Oral glucose tolerance test for diabetes

The oral glucose tolerance test is yet another method used to detect diabetes, but it is usually only done during pregnancy to diagnose gestational diabetes or for someone who is suspected of having type 2 diabetes yet has a normal fasting glucose level. It can also be performed to diagnose pre-diabetes.

HbA1c test for diabetes

The HbA1c, or glycated haemoglobin test, is an important diabetes blood test used to determine how well your diabetes is being controlled. This diabetes test provides an average of your blood sugar control over a six to 12 week period and is used in conjunction with home blood glucose monitoring to make adjustments in your diabetes medicines. An HbA1c reading of 48 mmol/mol (6.5%) is the recommended cut off point for diagnosing diabetes. A value below this does not exclude diabetes diagnosed using glucose tests.

WebMD Medical Reference

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