Living with Diabetes

Tests for Diagnosis

How are Diabetes and Pre-Diabetes diagnosed?

There are different tests that may be used to diagnose Diabetes and Pre-Diabetes. Test results indicating that a person has Diabetes should be confirmed with a second test on a different day.

If any of the diagnostic tests confirms that you have Pre-Diabetes, a stage before developing Diabetes, this means you are at a higher risk of developing Type 2 Diabetes. People with Pre-Diabetes can prevent or delay Type 2 Diabetes by losing a modest amount of weight, regular exercise and a healthy diet.

The following tests are used for diagnosis:

Fasting plasma glucose (FPG) test

The fasting plasma glucose (sugar) test is used to detect Diabetes and Pre-Diabetes. This test measures the blood sugar levels in a person who has not eaten anything for at least 8 hours.

Oral glucose tolerance test (OGTT)

The oral glucose tolerance test can be used to diagnose Diabetes as well as Pre-Diabetes. This test measures blood sugar levels after an overnight fast (8-14 hours) and 2 hours after the person drinks a sugar-containing liquid. The test should be performed after at least 3 days of unrestricted diet (> 150 g carbohydrate a day) and the person should be at rest during the test.

HbA1c test

The HbA1c is a simple blood test that does not require fasting and can be used for diagnosis of Diabetes and Pre-Diabetes. This test measures a person’s average blood sugar levels over a period of 2 to 3 months. 

Random plasma glucose test

The random plasma glucose test, also called casual plasma glucose test, measures blood sugar levels without regard to food intake. This test, along with the presence of classical symptoms of Diabetes such as increased urination, increased thirst, unexplained weight loss, is used to diagnose Diabetes but not Pre-Diabetes.

Diagnosis of Pre-Diabetes:

Impaired fasting glucose (IFG)
Fasting glucose
OR 
5.6 - 6.9 mmol/L
(100 - 125 mg/dL)
Impaired glucose tolerance (IGT)
2-hour glucose (OGTT)
OR
7.8 – 11.0 mmol/L
(140 – 199 mg/dL)
HbA1c 5.7 - 6.4%

Diagnosis of Diabetes:

Random glucose
OR

≥ 11.1 mmol/L
(≥ 200 mg/dL)

Plus the presence of classical symptoms of Diabetes (e.g. increased urination, increased thirst, unexplained weight loss)

Fasting glucose
OR
≥ 7 mmol/L
(≥ 126 mg/dL)
2-hour glucose (OGTT)
OR 
≥ 11.1 mmol/L
(≥ 200 mg/dL)
HbA1c ≥ 6.5%