Diabetes Lab Tests

Diabetes Lab Tests

Diabetes Lab tests

Written by: Dr. Claire Arcidiacono, ND

For further questions or concerns email me at [email protected]

Diabetes is ruled out or confirmed with blood tests. One of the most important tests is A1c or hemoglobin A1c (hA1C). This measures the average blood sugar levels over three months. Because the A1c is an average of the blood sugar levels over three months, it is considered more accurate for diabetes than a morning blood sugar reading or a spot test.  The reason for this is because, spot tests monitor your blood sugar for a very short period of time and are affected by what you eat. For example let’s say Monday you go to an ice cream all you can eat party, the next morning you test your blood sugar and it’s much higher than is healthy or normal. Meanwhile your A1c test results that you get in a few weeks shows you are fine. That is because A1c is an average, thus one or two days of sugar overload in most cases doesn’t affect the results. (1) †

Fasting blood sugar is a great day to day tool to make sure blood sugar is well controlled. Unfortunately unlike A1c it is affected by recent spikes in blood sugar. Therefore it is mostly used to monitor rather than rule out diabetes. It is also helpful when someone is having large spikes up and down in their blood sugar but overall the average blood sugar is normal. If there is a history of high fasting blood sugar this is an indicator that A1c should be tested. (2) †


Another blood test is called the glucose tolerance test and is used to determine how well your body is able to cope with glucose. This is actually a two part test. First is the glucose screening test. After fasting you are given a glucose liquid and 1 hour later your blood glucose level is tested. If the glucose level is higher than 140mg/dl, then a glucose tolerance test is recommended. Once again after fasting you will be given a glucose liquid. This time however you will get your blood sugar level taken first to get a baseline number. Then you consume the liquid and after 1 hour, 2 hours and 3 hours, your blood sugar levels are checked again. Depending on the results, an A1c can be used to confirm the diabetes diagnosis. Glucose tolerance tests are often done to screen for gestational diabetes. (3) †

Overall the most common tests for blood sugar are HA1c or A1c, fasting blood sugar, glucose screening tests and the glucose tolerance test. In addition to these tests, random blood sugar can be tested. (1) †

Now you may be saying what about the line on my urine test that says glucose?? Normally urine contains little to no glucose so anytime glucose is detected, it is flagged as abnormal. This is because glucose is not excreted by the kidneys. However when there is too much glucose in the body, the kidneys will get rid of the extra glucose by excreting it in the urine. While in the past, urine glucose was very important in monitoring blood sugar, (Just a random fun fact diabetes means sweet urine!). Due to its inaccuracies, it has become less common to use. It is useful when blood testing is too difficult for example in the case of needle phobias. Additionally urine tests can indicate the need for more accurate testing such as A1c. (4) †


In addition to glucose, the amount of insulin can be tested as well. Having too much insulin is called hyperinsulinemia. Having too much insulin can be a sign of insulin resistance, however I want to mention that other concerns such as tumors of the insulin producing cells can lead to an overproduction of insulin. (5) Low insulin is associated with type 1 diabetes. (6) †

I’ve included a chart for blood sugar numbers that indicates normal, pre and diabetic numbers so that as we get more into this topic a reference range is already available.(7) †

Next week we will be talking about Type 1 diabetes which was formally called Juvenile diabetes! †


  1. https://www.cdc.gov/diabetes/managing/managing-blood-sugar/a1c.html\
  2. https://www.cdc.gov/diabetes/basics/getting-tested.html#:~:text=Fasting%20Blood%20Sugar%20Test,higher%20indicates%20you%20have%20diabetes.
  3. https://www.mayoclinic.org/tests-procedures/glucose-tolerance-test/about/pac-20394296
  4. https://medlineplus.gov/lab-tests/glucose-in-urine-test/
  5. https://www.mayoclinic.org/diseases-conditions/type-2-diabetes/expertanswers/hyperinsulinemia/faq-20058488
  6. https://www.testing.com/tests/insulin/
  7. https://www.cdc.gov/diabetes/basics/getting-tested.html

Share this post!

Leave a Reply

Your email address will not be published. Required fields are marked *

This site uses Akismet to reduce spam. Learn how your comment data is processed.