Learn How to Test for Diabetes

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When looking for a way for how to test for diabetes, several options are available. Each is slightly different and may be used for different circumstances. If one test shows a positive result for diabetes, a second test must be used to confirm the diagnosis. A diagnosis of diabetes is usually not made without two positive test results.

Fasting Plasma Glucose Test

One test, the fasting plasma glucose (FPG), is commonly used. Everyone has spikes and dips in their blood glucose levels in response to food consumption. This test measures blood glucose levels after an extended fast, which evens out the results.

To take the test, your physician will have you schedule a time to test. Prior to that test, you will need to fast for a minimum of 8 hours, and sometimes up to 12 hours.

Blood is drawn after the fasting and sent to a lab to be analyzed. Blood glucose levels less than 126 mg/dL usually indicate that the patient is not diabetic. Blood glucose levels higher than 1226 mg/dl may indicate the presence of diabetes. Many physicians may order more than one test to confirm a diagnosis.

Casual Plasma Glucose Test

This test is casual in that no fasting is required prior to the test. It can be administered at any time, regardless of when the patient last ate or drank anything. The level considered good (non-diabetes) is less than 200 mg/dL.

Oral Glucose Tolerance Test

This test is administered to pregnant women in order to screen for gestational diabetes, and is also sometimes use in difficult diagnostic instances not related to pregnancy. Pregnant women are asked to fast overnight. They are then given a very sweet liquid to drink. It is glucose, but can taste like non-carbonated soda syrup or orange soda that has lost its fizz. After the liquid is consumed, the blood of the pregnant woman is drawn multiple times (usually up to 4) in order to measure the blood glucose levels of the patient.

A blood glucose level of lower than 140 mg/dL is considered to be good or normal.

Home Testing

One method that is used at home to help determine if glucose is in the urine involves the use of urine glucose test strips. It is not recommend to use these, though, because the blood glucose level can be quite high to show up on the test strip as a positive result. At this point, the patient may already be in medical danger.

If diabetes is suspected, a visit to the physician is in order. This is because diabetes is a serious disease that, if left untreated, can result in complications such as diabetic retinopathy, kidney failure and heart failure.


How to test for diabetes can be accomplished in a number of ways, depending upon factors such as if you are a pregnant female or have eaten recently. Your treating physician can recommend the best test for you to help screen for and diagnose diabetes. The most accurate testing is the kind ordered by a physician.


Diabetes Guide: Diabetes Testing. WebMD. https://diabetes.webmd.com/guide/diagnosing-type-2-diabetes

Diabetes: Tests and Diagnosis. Mayo Clinic Staff. March 17, 2010. https://www.mayoclinic.com/health/diabetes/DS01121/DSECTION=tests-and-diagnosis