Blood glucose testing is also known as blood sugar tests. They can be performed after fasting or as part of an oral glucose tolerance test. They are typically used to diagnose or monitor diabetes.

What is being evaluated?

This test detects the amount of glucose in your bloodstream. Glucose is a simple sugar that supplies energy to the body.

People with diabetes frequently test their blood glucose levels at home. This is accomplished utilizing a finger-prick test and a specific machine instead of a blood sample drawn from a vein.

get a blood test

You may have blood drawn to determine your blood sugar level. You may or may not be required to fast beforehand.

In addition, there is a test known as the oral glucose tolerance test, abbreviated as OGTT or GTT. For this test, you will fast, have a blood sample drawn, and then consume glucose, followed by a series of blood pulls over several hours.

Why would I need to take this exam?

This test may be necessary if you are at risk for developing diabetes or if you have diabetes-related symptoms or test findings.

Standard blood glucose testing examines your blood sugar level at a specific time. The OGTT measures your glucose sensitivity.

Women who develop gestational diabetes will be invited to undergo an OGTT between 24 and 28 weeks of pregnancy. Gestational diabetes typically disappears after delivery.

If your glucose level remains above, then you have diabetes. Hypoglycemia is the condition that occurs when the glucose level falls too low.

The principal blood glucose measurement tests are:

  • the random blood glucose level
  • Blood glucose level during the fasting state.
  • The HbA1c blood test
  • Oral glucose tolerance tests
  • glucose levels in capillary blood (home monitoring).
  • Urine test for glucose (glucose).
  • Blood testing for glucose levels (glucose)
  • The random blood glucose level

If diabetes is suspected, a blood sample collected at any time might be a useful diagnostic tool. Diabetes is indicated by a blood glucose level of 11.1 mmol/L or above. To confirm the diagnosis, a fasting blood glucose test may be performed.

Fasting blood glucose

A random blood glucose level below 11.1 mmol/L does not rule out diabetes. A blood test conducted in the morning before breakfast is more accurate. Eight to ten hours before a fasting blood glucose test, only water should be consumed. At or above 7.0 mmol/L, diabetes is present.

If there are no symptoms of diabetes, but the blood test reveals a glucose level of 7.0 mmol/L or more, the blood test must be repeated to confirm diabetes. If you experience symptoms and your blood glucose level is seven millimoles per liter or above, the test does not need to be repeated. Refer to the individual pamphlets Type 1 Diabetes and Type 2 Diabetes for additional information.

Oral glucose test

This test is no longer often used to detect diabetes. However, the test may be performed if it is believed that your body does not handle glucose levels typically but not severely enough to be diagnosed with diabetes. This is known as pre-diabetes (impaired glucose tolerance). The test may also determine whether a woman has developed gestational diabetes.

For this examination, you must fast overnight. You are given a beverage containing 75 grams of glucose in the morning. Two hours later, a blood sample is drawn. Usually, your body should be able to process glucose, and your blood sugar level should not rise excessively. Diabetes is indicated by a glucose level of 11.1 mmol/L or above in a blood sample collected after two hours.

HbA1c blood test

If you have diabetes, your doctor or nurse may check your HbA1c level every two to six months. This test measures your current average blood glucose level. Because it is a mean measurement, you do NOT need to fast on the test day. The test measures a component of red blood cells. Blood glucose binds to a portion of red blood cells. This component is measurable and provides an excellent estimate of your typical blood glucose over the past two to three months.

HbA1c readings were previously given in percentages under the Diabetes Control and Complications Trial in the United Kingdom (DCCT). The non-diabetic “normal” range is between 4% and 6%.

Since June 1, 2009, HbA1c readings in the United Kingdom have been standardized according to the International Federation of Clinical Chemistry and Laboratory Medicine (IFCC). The comparable normal, non-diabetic range is 20-42 mmol/mol.

Home monitoring

A drop of blood from a finger prick is placed on a test strip containing a reagent that reacts with glucose. The blood glucose level can be measured rapidly using a color chart or a small glucose meter. Monitoring at home is crucial for anyone with diabetes who requires insulin medication.

Urine test for glucose (glucose)

Normal kidney-produced urine does not contain glucose. The kidneys filter our blood, retaining things the body requires while eliminating waste. Your kidneys continually reabsorb glucose so that it does not enter your urine. However, if the glucose level exceeds a specific threshold, the kidneys cannot absorb all of the glucose. This means that some glucose will “leak” through the kidneys into the urine.

A simple dipstick test can detect glucose in urine samples. A physician or nurse dips a specific chemical strip into a urine sample in a dipstick test. Changes in color on the strip indicate whether or not a urine sample contains glucose. Diabetes is likely if glucose is detected in the urine.

However, some people have more “leaky” kidneys, and glucose can leak into urine even with an average blood glucose level. If your urine includes glucose, you should get a blood test to determine your blood glucose level to confirm or rule out diabetes.


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