Glucose Tolerance & A1c are confusing

[lewisjl]

I have posted a couple of times and now have a new question. I was diagnosed hypoglycemic about 15 years ago and haven't watched my diet in quite a while. A couple of months ago, I had a feeling that my blood sugar was getting wacky & so I started testing again and was testing a bit high. I had 2 times where I felt funny (was not sick), similar yet different to hypo symptoms. I tested at 200 & 215. So I went to my doctor & my A1c came back 5.6 (122)....yeah for me, but I didn't understand why because I thought it was going to be higher than that. After posting on this forum, some of you convinced me to follow up with a glucose tolerance, which I had done yesterday.

Now I am even more confused because my NEW meter is so screwed up. I took it to the test and my meter tested fasting, 30 min, 1 hr, 2 hr, 3 hr at 101, 153, 161, 116, and 105. I was thrilled, thinking that my blood sugar was pretty good. HOWEVER, the doctor's office called this morning & said everything was normal. I politely asked them to fax me the results and they were 94, 154, 96, 79, and 70. Ok.....so first of all, the doctor's office says that is normal? Secondly, my meter is 32-41% off!!! Of course that gives me no confidence in any testing I have done since I got my new meter! Also, I was not remotely shaky or confused or having any reaction to being at 70. How can I be getting that low and have an A1c of 5.6? Do I need to be concerned with these numbers?
Thanks in advance for your responses!!
Janet

[sorka]

If you go by the lab's result, you're not even pre-diabetic. Those are perfect numbers. What was the diagnostic criteria used to decide you were pre-diabetic?

Your meter is more likely to be that far off than the lab is. I have 3 meters and cross check them with each other as well as running the calibration test with the glucose control solution to make sure their accurate. I also test them against the lab.

My meter is always within 2 or 3 points and sometimes even closer to the labs.

[sorka]

Oops. I see. A1C of 5.6. Although you can still have an a1c that high and not be pre-diabetic but it is on the higher side of normal.

[ADSOFT]

. How can I be getting that low and have an A1c of 5.6? Do I need to be concerned with these numbers?
Thanks in advance for your responses!!
Janet

Well, I'm an Engineer and I have looked at lot of waveforms of regular non diabetics, Pre-D, D's, and really Bad D's.

Pre-D's start out at a normal range, but there waveforms, ring more than a strong non D.

You went over 150, from the waveforms I have seen, if a Pre-D has a large meal, 4 hrs later they have a low since their system starts to respond slowly to large Carb loads, ... those close to 75 grams.

It seems that you don't eat heavy carb loads but are starting to get D. If you are getting lows below 80 4 hrs after a large meal that would be typical Pre-D behavior.

So, basically since you eat low carb loads you have a low A1C, but if for the next 3 mos you eat meals close to 75g of Carbs (or more) with high glycemic indexes, that A1C should go up.

... Try checking you BG at 4-5 hrs after larger meals, it will give you a lot of info.

[fgummett]

After 6+ years of actual personal experience with Type 2 D and literally thousands of BG tests I'd say not to worry too much but to be aware...

Firstly there are several reasons why BG readings can be way off without it being the fault of the meter itself: contamination (food, dirt, sweat, alcohol etc...) on the finger, too little blood, too much squeezing so you also get serous fluid -- just as examples. It's a fact of life that we all just learn to live with and somehow we get some pretty good BG control even allowing for the level of inaccuracy. It's a darn sight better than before home BG meters when all they had to rely on was urine tests which showed that you had so much excess BG that it was spilling out of your kidneys ;)

Secondly 70mg/dl is at the low end of the Normal range (70-125) so there is not expectation to feel hypo at that level.

BUT if I had your BG readings today I would be concerned enough to take it as a wake up call that I am likely heading towards D and should look to my diet and activity levels now... it is far easier to lower the water pressure on a dam than try to shore it up after it has burst. And that doesn't mean crazy fad diets or killing yourself at the gym 5 nights a week... just focus more on real whole foods (local and in season) with minimal refined/concentrated carbohydrates and go for a brisk walk on most days... park the car further from the store entrance, take the stairs etc... changes that you can live with for the rest of your long and healthy life.

Here is a related thread you might find interesting http://www.diabetesforums.com/forum/type-2-diabetes/35533-timeline-normal-prediabetic-full.html

[jer.lawrence]

as well as running the calibration test with the glucose control solution to make sure their accurate.

This may not be the thread for this, but could you explain that further? I sometimes wonder how accurate my meter is (I only have the one) and am now far more curious whether there's a way to tell.

Thanks.

[patricia52]

What kind of meter. I called AccuChek and the sent me 2 control solutions. One for High and one for Low. When I got the solutions I was to call them back. They walked me through the entire process on the phone. It was easy.

[jps]

The worst lab analyzer is going to be more accurate than the best home meter. They should match up relatively well, however. By relatively well, I'd say within 20%.

So which do you trust? Well, it should all be relative. For diagnosis, I'd rely on the lab analyzers. For monitoring daily, obviously you have no choice but you use the meter, but it's fine because it's relative anyway. Though it may not be 100% accurate, it will give you a strong idea if you are high, low, going up, coming down, etc.

Also, the lab analyzers and home meters are going to match best at a range of 80 to 200 or 300. Once you start hitting the upper and lower end of linearity (linearity refers to the span of values that can be read), there is going to be more variance. For instance, a 500 on your home meter could very well be a 700 (about a 30% difference) in the laboratory, whereas a 150 on your meter might only be a 165 (10 percent difference) in the laboratory.

Using the QC material (one that hasn't expired) is good enough to verify the accuracy of the home meter. I'd be concerned if the QC material is consistently on the high or low end of the acceptable range however, because it means that though it's accurate, there is probably a bias and recalibration needs to occur - or the meter needs troubleshooting (which usually means a new meter to be honest).

I have to evaluate QC on a daily basis on many analyzers. QC should have pretty random scatter above and below the mean to be optimal. In other words, if the mean of my QC material is 100 and the acceptable range is 90-110, I like seeing values such as 97, 104, 99, 102, 100, 96, 103 rather than 91, 92, 93, 92, 91, 90. The former shows more reliability, the latter shows a probable slight bias, meaning that the personal readings you are getting from your meter are probably a little bit lower than what they should be.

[fgummett]

I remember I railed against the frustrating inaccuracy of home BG meters when I first started here on DF and was politely pointed towards a $600+ unit from Scandinavia (IIRC) with each test (which needed to be kept in a fridge) costing several dollars.

As I mentioned above, home BG testing is far superior to the old urine tests, but it is what it is... you want [relatively] cheap, fast, easy and convenient..?

Even in terms of the acceptable range for the control solution.. I have my Contour test strip bottle here and it states that the control range is anywhere between 109-150 mg/dl (6.0-8.3mmol/l)... for a controlled solution.