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Avatar universal

False positive tests vs 2 glucose monitors

Greetings

During a yearly check-up, my bloodwork showed higher than average glucose levels (7.1). I was then asked to take a GTT ( 2 hour) and the lab results came back as 10.8!

My husband is a Type 2, uses insulin and has glucose monitors. They do appear to be working. So, for the past 4 weeks I have been taking morning readings and after meal readings and they are in the 4-6 range which I gather is normal. The A1c test registered 5.6. My GP is convinced I have diabetes and when I did a follow-up appointment and showed her my levels that I put on a spreadsheet, she said she didn't have time and dismissed my concerns and queries. She wanted to put me on Metformin even before the A1c.

Is it possible that the first two tests were wrong? I have another appointment with a new GP who was highly recommended to me and I would like a second opinion. It is not that I am in denial, more like the lab findings and the weekly/daily readings tell me something otherwise. This is rather perplexing.

Anyone else have this experience? I suppose I would rather this scenario be a proverbial wake-up call than something definitive for the time being.

Thank you.
14 Responses
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Avatar universal
Thanks for your answers and once I consult the new GP in November I will get back to you all.
Helpful - 0
141598 tn?1355671763
You may consider it bickering or whatever you wish to call it. I don't feel this discussion belongs behind closed doors and should be informative to readers on what's new and correct in determining their glucose test levels.

Although the A1C test is an important tool, it can't replace daily self-testing of blood glucose. A1C tests don't measure your day-to-day control. Estimated Average Glucose (eAG) is a new way to understand how well you're managing your diabetes. How does it relate to A1C?

If one has Type 2 diabetes, they may know about the A1C test that tells you your average blood glucose over the past 2 to 3 months. Now we have a new way to report A1C called estimated average glucose, or eAG. eAG uses the same units (mg/dl) as your glucose meters. A patient cannot and should not accept 137 mg/dl [7.6 mmol/l] as prediabetes, the equivalent of 6.5% A1C. That is wrong and unhealthy to do so.

By the way, on Nov 2 the ADA will have a new updated web site. Go here for the ADA A1C to eAG chart. http://alturl.com/nvnxy
Helpful - 0
Avatar universal
I'm sure you have excellent doctors and they are perhaps at the forefront of changes in diagnostic criteria. I agree that the definition of diabetes and pre-diabetes as well as the tests to determine it continues to change. But until the commonly accepted standard is changed officially (the figures I quoted are not just from one website; I just included that one is a well recognized organization). Until they are changed, I think it is the most useful to tell newcomers the commonly recognized diagnostic criteria which remains: pre-diabetes 5.7-6.4 and diabetes over 6.5).

You are welcome to disagree and follow a new standard that may in time be adopted but as of now is not in common use. But I feel this is confusing to newcomers. I think at this point we are getting into personal disagreements which is not useful for anyone so if you wish to discuss this further we can do so in PM. I won't continue to bicker on a public board.
Helpful - 0
141598 tn?1355671763
"THIS is the standard that is still in official use by the ADA and by every doctor and endo I have ever heard."

As I stated in my previous post two doctors [Directors of Endocrinology School of Medicine] at two major teaching university hospitals have accepted eAG. Some people find it hard to accept changes and tend to become biased to past standards. The purpose of reporting eAG is to help you relate your A1c results to your everyday glucose monitoring levels. The American Diabetes Association has adopted this calculation and provides a calculator and information on the eAG on their web site. Yes, the ADA web site chart still reflects 5.7% - 6.4% (39 - 46 mmol/mol) but that is soon to change as web sites get periodic updates/changes. Also keep in mind, the ADA web site is sponsored by all the major drug firms. To keep values high increases the chance of more drugs prescribed to patients.

Eight years ago the 'acceptable' standard for diabetes screening was not an A1c but fasting and/or an OGTT. Although the latter two is still in use today, they are fast becoming outdated as the A1c converted to eAG takes over. The bottom line is what is the patients daily average glucose. The only way to determine that is to convert the A1c to eAG. Doing so the 6.4% is HIGH
and screams diabetes, not prediabetes.
Helpful - 0
Avatar universal
I thought I'd give it a try, because sometimes websites are allowed and I think it is very important people receive the correct information: http://www.diabetes.org/diabetes-basics/prevention/pre-diabetes/how-to-tell-if-you-have.html

This is the ADA website, which is the determinant of diagnostic standards, at least in the U.S. I could post others, but there is only so far I will go to prove something that is known by many people and information that is easily available in many places.

Pre-diabetes is 5.7-6.4 and diabetes is 6.5 and over.
Helpful - 0
Avatar universal
I'm sorry but I disagree. That is the standard range listed in several places including the ADA. While particular doctors may use a different standard - and I certainly commend them if it helps catch more people with pre-diabetes at an earlier stage, THIS is the standard that is still in official use by the ADA and by every doctor and endo I have ever heard. Diabetes diagnosis is not a matter of opinion, it is driven by very specific numbers and the ones I have quoted are the numbers used. I could post numerous sites to verify this but I am not allowed to post websites on this board. You are the one that is posting misleading information and I'm sorry if it offends you to be corrected but I want to make sure that people that come new to diabetes to this forum aren't told incorrect information.
Helpful - 0
141598 tn?1355671763
The prediabetes A1c range you post is high and outdated. I conversed with three doctors, two at major teaching hospitals and my Endo. All three said they convert A1c to eAG and follow the ADA formula to determine a patients daily glucose level over the past 3 months. In my previous posts I have shown that your ranges are high. To keep quoting higher than normal prediabetes A1c ranges is misleading & confusing to the readers of this forum.
Helpful - 0
Avatar universal
It wasn't the eAG I was referring to, but the A1C numbers used for diagnosis of pre-diabetes and diabetes which is 5.7-6.4 for prediabetes and 6.5 and over for diabetes.
Helpful - 0
141598 tn?1355671763
"A1c of 5.7-6.4 is considered pre-diabetes and 6.5 and over is diabetes."

I used the ADA [American Diabetes Association] eAG online calculator for the following:

The equivalent of 5.7% A1C is  6.5 mmol/l eAG. [117 mg/dl]
The equivalent of 6.4% A1C is 7.6 mmol/l eAG. [137 mg/dl]

Prediabetes range
The equivalent of 5.1% A1C is 5.5 mmol/l eAG. [100 mg/dl]
The equivalent of 6% A1C is 7.0 mmol/l eAG. [126 mg/dl]

Helpful - 0
231441 tn?1333892766
COMMUNITY LEADER
Another comment:  if you are indeed prediabetic, metformin may not necessarily be a bad choice, combined with diet and exercise measures.  Together they may keep things stable for a long time.

However, it is right to look into this closely.  You don't want a diagnosis of diabetes if you don't have it.


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Avatar universal
Actually for purposes of diagnosis (for which it is now the test of choice), A1c of 5.7-6.4 is considered pre-diabetes and 6.5 and over is diabetes.
Helpful - 0
141598 tn?1355671763
Yes, definitely run as fast as you can from your previous doctor and get retested at the new doctors office. An OGTT [GTT] to me is a waste of time and should rarely be used. Get a fasting plasma glucose test because this test is simpler, more accurate, less expensive, and less variable than the OGTT.

Normal fasting range = 3.3-5.5 mmol/l <---where you want be
Prediabetes range = 5.6-6.9 mmol/l

Include in the same blood draw [sample] an A1c test then use this formula to see your estimated daily average glucose [eAG] as compared to your fasting glucose results level.

28.7 X A1c – 46.7 = eAG
Then divide by 18 or multiply by 0.055 to see your mmol/l results.

A1c normal range = <4.9%
A1c prediabetes = 4.9-5.5% [5.6-6.9 mmol/l]

Helpful - 0
Avatar universal
I definitely agree that a doctor who "doesn't have time" to listen to you is not a good doctor for you. I'm a little confused about your numbers, especially since you use the Canadian numbers and it's easy to confuse them with A1Cs. What type of test was the 7.1? Was that an A1C or a fasting blood sugar. If the latter, yes 7.1 (127.8) fasting is just into the diabetic range. (126) The OGTT is just under the definition of diabetes (200). The 10.8 is 194.4 and makes it pre-diabetic. However the A1C you report 5.6 is under even the pre-diabetes level (starting at 5.7). The A1C is the standard for diagnosis of pre-diabetes and diabetes. So what I see in these numbers and the ones you report at home is that something is happening for sure but a diagnosis of full diabetes (rather than pre-diabetes) might be premature. If you have pre-diabetes you might want to start by trying to control it with reduction of carbs, exercise and weight loss if needed. For many people (not all) this will keep the pre-diabetes from advancing.
Helpful - 0
Avatar universal
Hi Adelaide,
There are many people on here who are very knowledgeable and make say more to help you.  I will just give you my 2 cents. You  absolutely did the right thing by going to a 2nd doc. I do not have diabetes, however I'm an RN. It is vitally important that you get a correct diagnoses. As you must know Diabetes is nothing to fool around with. Glucose monitors are not your most reliable source, especially if you don't do the required quality controls.  I'm not putting them down, but the blood drawn at the lab value is more reliable. Also, you should have fasted the night before. NOTHING to eat or drink except water. Good luck in your endeavor you will get a correct result if you follow what I have just told you. the 2hr GTT test is very good anf forget that first doc who didn't have time to be bothered.
Helpful - 0

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