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Dr. Andrew Rynne

Family Physician

Exp 50 years

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What does abnormal three hour glucose test indicate?

Answered by
Dr. Shehzad Topiwala


Practicing since :2001

Answered : 1663 Questions

Posted on Sat, 16 Aug 2014 in Thyroid Problem and Hormonal Problems
Question: I am seeking an opinion regarding the results of a recent glucose tolerance test I had. For 3 years I have suffered from numerous symptoms and have had numerous tests/scans with no results as far as a diagnosis goes. Upon researching many of the symptoms many of them are associated with Diabetes. My neurologist recently ordered a 3 hour glucose test which came back as abnormal. My 2 hour result was 170 when 150 or below was considered normal. My 3 hour number was the maximum number for normal but I forget exactly what it was. The neurologist office sent me the lab (which was flagged abnormal) but when I called to follow up the nurse said that the deviation in the result was not concerning. I'm sure she asked the Doc about this but I have no follow up with him. I would like to know if the result is possibly indicative of diabetes. I have read that 200 or higher would have been but I really don't have anything else to go on. If it is not diabetes what does the abnormal result mean?
Answered by Dr. Shehzad Topiwala 1 hour later
Brief Answer:
Pre diabetes

Detailed Answer:
There is a condition called pre diabetes that has specific diagnostic criteria just like there are clear cut offs for making a diagnosis of diabetes. The stabdard test for both thee conditions is called the 2 hour 75 gram Oral Glucose Tolerance test. This is perfirmed after an overnight fast of 8 to 14 hours. Drinking water is okay. The thresholds for diagnosis are as follows : fasting glucose value : 65 to 99 is Normal. 100 to 125 is called impaired fasting glucose. 126 or more is compatible with diabetes. Then 75 grams glucose is given with water and exactly at 2 hours a blood sample is taken. During this time one is supposed to be seated and none of the following is permitted : walking, smoking , eating, coffee etc. Only water is allowed. The cut offs at the 2 hour mark are as follows : less than 140 is normal. 140 to 199 is called Impaired glucose tolerance. 200 or more is considered to be diabetes. Now bear in mind that it is recommended that testing is repeated on a second occasion to be certain of the diagnosis. The whole glucose tolerance test need not be repeated. Either fasting or 2 hour post glucose can be done. There is a third screening blood test for diabetes called HbA1c. Even this can be used to make a diagnosis of diabetes versus pre diabetes. Less than 5.7% is normal. 5.7% to 6.4% is pre diabetes and 6.5% or more is tantamount to diabetes. The two terms above 'Impaired fasting glucose ' and ' Impaired glucose tolerance ' are also equivalent to diabetes. I don't see what your fasting glucose value is. I see you have mentioned that your 2 hour glucose reading was 150. If the test was performed using standard guidelines then your reading falls in the range of Pre diabetes
Above answer was peer-reviewed by : Dr. Chakravarthy Mazumdar
Follow up: Dr. Shehzad Topiwala 19 minutes later
I have reviewed my results again. My fasting number was 97 when 70-110 was the normal range. My 1/2 hour was the high number at 150 when 70-139 was the normal range, my 1 hour reading was 139 when 70-140 was considered the normal range and my 2 hr reading was 97 when the normal range was 70-139. The 150 reading was flagged as abnormal while the others were marked normal. Does pre diabetes have similar symptoms to diabetes? I have had numerous bothersome symptoms in the past 3 years I won't list them all here but neuropathy sums up many of them. I am a successful practicing attorney with my own office and it has been a struggle to keep things running with the issues I am having. I thought maybe I finally had a diagnosis when I saw the lab result but since the neurologist never called me back he obviously didn't believe it was diabetes. I appreciate your time reviewing this lab for me and any light you can shed for me is likewise appreciated.
Answered by Dr. Shehzad Topiwala 24 minutes later
Brief Answer:
Follow up

Detailed Answer:
I am happy to note your successful professional life.

I am sorry to hear about the medical problems you are facing that have evaded a proper diagnosis thus far.

As alluded to above, based upon standard endocrine practice guidelines, you do not have diabetes nor pre diabetes. Pre diabetes does not have any specific symptoms. it is typically precursor to diabetes, as the name suggests but it can be present along with other metabolic conditions like high blood pressure, high cholesterol and overweight/obesity.

It appears you have had a thorough evaluation but just make sure the following tests have XXXXXXX done and are normal:

Once it is clear that your hemoglobin,liver, kidney and electrolytes are normal then just have a documented blood test for thyroid (TSH, Free T4) and vitamin D. Insufficiency of either can produce symptoms similar to the ones you are experiencing

Above answer was peer-reviewed by : Dr. Chakravarthy Mazumdar

The User accepted the expert's answer

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