4 methods of testing blood sugar

So you’ve decided that you need to be tested for diabetes. Where do you even begin? There’s so much information out there and so little time—what you need to know can be just a little overwhelming. This guide shows you what sort of tests you need in order to determine whether or not you have diabetes, and what to do once you’re tested.

The following are a list of tests considered by the American Diabetes Association to be the criteria for the diagnosis of diabetes, with the values determining diagnosis taken directly from their website. As such, this list should be used for informational purposes only, not as a substitute for genuine medical advice.

Fasting blood sugar (FBS)

This test measures your blood sugar 12 hours after your last meal, with an 8-hour minimum. During this period you will be expected to eat nothing and drink only plain water—even sugar-free drinks containing caffeine can interfere with the results of the final reading, and are not recommended for consumption.

 A FBS reading of 126mg/dL, or 7.0 mmol/L, means you may be diabetic.

Oral glucose tolerance test (OGTT)

A preliminary requirement before undergoing this test, fasting for 8-12 hours is a must. A baseline reading is then obtained by taking an initial reading of blood sugar. You will be given a glucose solution calculated by your body weight that you are expected to finish within 5 minutes. Another blood sugar reading will be taken 2 hours later and compared to the baseline reading to obtain the final results. Your blood may be collected for up till 6 hours depending on your doctor’s requirements, although this is rare.

 A OGTT reading of 200mg/dL, or 11.1 mmol/L, means you may be diabetic.

Random blood sugar (RBS)

Also known as a casual blood test, there are no preparations needed beforehand. This test already takes into account a non-fasting state beforehand, in addition to assuming normal values. A RBS test may be conducted multiple times to facilitate diagnosis, and has the same benchmark as the OGTT.

A RBS reading of 200mg/dL, or 11.1 mmol/L, means you may be diabetic.

Glycohemoglobin A1C (HbA1c)

A test involving the reading of a glycated hemoglobin in the bloodstream that, when measured, indicates the average plasma glucose concentration over a long period of a time. It is unique among blood tests in that it is also used by those who are already diabetic to measure their progress with the condition, usually required for up to two times a year in order to obtain an accurate result.

The preparation for an HbA1c test is different as it requires a baseline of stability with regards to diet, treatment, and routine for a minimum of 6 weeks before accurate HbA1c readings can be obtained. Those who have also recently donated blood or lost large amounts of blood for any reason should not take this test, as the replenishment of blood within the body does not portray an accurate amount of glycohemoglobin.


A A1C reading of ≥6.5% means you may be diabetic.

Therefore, as can be seen from the above listed blood sugar tests, there are numerous ways in which you can be tested for diabetes. Knowledge is power, and an awareness of what each testing process entails can be helpful and empowering in getting treatment