Difference in readings within 30 secs

dlife · #1 (**permalink**) 01-03-2009, 03:05 PM

I haven't got the prescription for my testing meter and supplies from my doc yet. So, in the meantime I purchased Reli on Ultima from walmart and started testing. The numbers were close to the time when I was diagnosed a month ago but my symtoms are getting worse like feeling more lethargic, low and dizzy all the time.

I was wondering whether the meter is working well or not. So today I tested 3 times within three minutes. There was barely one minute gap between each test.The reading were 107 first time, 138 second time and 159 mg/dl third time. The test was taken 3 hours post lunch.

How is it possible...why did it show such a difference between each time within one minute? So does that mean the meter's wrong or am I missing anything here? Thanks.

Keezheekoni · #2 (**permalink**) 01-03-2009, 03:10 PM

The accuracy rate has a +/-20% margin. So, those numbers are all within that range.

If you want a more accurate test, do the three different tests using the same drop of blood.

Subby · #3 (**permalink**) 01-03-2009, 05:45 PM

Quote:

Originally Posted by Keezheekoni

The accuracy rate has a +/-20% margin. So, those numbers are all within that range.

If you want a more accurate test, do the three different tests using the same drop of blood.

That would probably produce closer numbers... but how would it be more accurate?

dlife · #4 (**permalink**) 01-03-2009, 06:34 PM

Would the bg level differ in each drop of blood? Actually the last two readings are from same drop of blood.

Is the +/-20 range difference possible in the same meter??

So what should I take as my correct reading amongst all the three I listed above?

Subby · #5 (**permalink**) 01-03-2009, 07:01 PM

Quote:

Originally Posted by dlife

Would the bg level differ in each drop of blood? Actually the last two readings are from same drop of blood.

If the blood does actually differ slightly, then it's also reflecting your own BG, so I wouldn't worry about it. You can't claim on the spot that a test from one site is more "accurate" than a test from another. Unless the second site has food on it... but then the first may as well. I'd just ignore this issue, myself, concentrate on having clean hands if that is a possible issue.

Quote:

Is the +/-20 range difference possible in the same meter??

Yes, that is what was meant. I don't know of a particularly accurate meter. There are better and worse ones. I've found my accuchecks replicate closer numbers than other brands. But that's just experience and personal knowledge. They still officially have a wide margin of error.

If I were you, I'd try this again to see if it's not normally a bit more consistent, and if you feel like blowing cash before your prescriptions, get your hands on another brand of meter, give that a go.

Quote:

So what should I take as my correct reading amongst all the three I listed above?

None of them - that's the point. Having taken three though, you're probably best to take the average to work with. More meaningful is to consider BG tests over a range of time, (say all fasting or all post meal over 4 days) - the inaccuracy should in general be minimised and you will get a good "fuzzy" picture - which is generally adequate. Accuracy aint everything.

dlife · #6 (**permalink**) 01-03-2009, 07:45 PM

Oh, thanks subby. I didn't think about this until today when I almost accidentally checked thrice. I recently started testing just 2 weeks back. Never tested more than once within one hour. And believed whatever he reading showed was the accurate one. Now I am very confused as to what to believe...The difference in readings today was not small, the first reading was 107 mg/dl whereas just after a min it showed the reading as 159 mg/dl!!! I am clueless now.

momaniamer · #7 (**permalink**) 01-03-2009, 09:32 PM

In fact it is highly recommended to keep 10-15 minutes time gap between readings,also to take readings after two hours,just relax and don't drive your selfe in worries and negative thinking,just relaaaaaaaaaax.

EeyoreButterfly · #8 (**permalink**) 01-03-2009, 10:56 PM

Did you test on your fingertips or another part of your body? If you test fingertips then arm for instance, you will get different readings because the fingertips register changes in sugar levels faster (the reason you must test on your fingertips when feeling hypo).

I've not had a meter that had that kind of variance from test to test. If I did, I would go absolutely nuts. Meters have to be accurate to within 20% of lab values, but you want a meter that is consistent as well. Go to the monitoring board and look at the post where I gave the Consumer Reports ratings for meters. Consistency was one of the categories they tested, as was accuracy (compared to lab values). Surprisingly, ReliOn was close to the top, so it could be that you have a bad meter.

Did you wash your hands before the first test? Did you have lotion on your hands? Make sure to wash your hands before you test and not to apply lotions before testing. This will give you more accurate and consistent readings.

Subby · #9 (**permalink**) 01-03-2009, 11:01 PM

I suppose you need to consider you might have a bad batch of strips, too. It's got to be possible.

kmac · #10 (**permalink**) 01-04-2009, 08:59 AM

I often wonder why they csnnot make a more accurate meter (??????????) They can make a talking meter and a meter that is tiny or one that you can order in a colour to match your colour scheme. + or - 20% seems such a huge variation but perhaps I don't understand the problems that need to be surmounted in order to do this.

dlife · #11 (**permalink**) 01-04-2009, 09:40 AM

Momaniamer, ok I would try with that time gap.Eeyorebutterfly, I saw your post and yes Reli on was on top 4. May be I got a bad meter. I do wash my hands everytime I test. Subby, as you said, I am finally getting a hang of it. I am getting the "fuzzy picture" lol. For instance today morning my readings were 101 and 133 at the same time. So now I guess I should be somewhere in between, right?
Kmac, yes, it would greatly help us if there were accuarate meters.

Thanks guys for listening to me. I am a bit relaxed now.

dlife · #12 (**permalink**) 01-04-2009, 09:42 AM

Eeyorebutterfly, I test only on fingertips.

EeyoreButterfly · #13 (**permalink**) 01-04-2009, 10:03 AM

dlife: You will drive yourself bananas with all these multiple testings, not to mention how expensive strips are. For now just do one test. You will know that it is a ballpark figure, but it can least give you a rough idea of what your blood sugar is doing until you can get a different meter.

JediSkipdogg · #14 (**permalink**) 01-04-2009, 10:30 AM

Quote:

Originally Posted by kmac

I often wonder why they csnnot make a more accurate meter (??????????) They can make a talking meter and a meter that is tiny or one that you can order in a colour to match your colour scheme. + or - 20% seems such a huge variation but perhaps I don't understand the problems that need to be surmounted in order to do this.

There is one that is very accurate. It's called the Hemocue Glucose 201. There's a few catches though....

1) The meter itself is not "compact" in that it's about the size of an old school original Gameboy.
2) The meter costs $400-$700, not covered by insurance
3) The strips costs $130 for 100, not covered by insurance
4) The results take about 60 seconds to return
5) 5 µL of blood is required, the most any meter now requires I think is 1 µL. So might as well bring the knife out and start cutting.

All of those add up to the higher accuracy. In general though people will think they have gone back in time, however, if you truely look at it, other companies have sacrificed accuracy and precision for what people want more, and that is money, fast results, small sample sizes, etc. Want accuracy and precision? Pay up for it.

Side note....this is one reason I don't think continuous glucose is ready for the mainstream yet. It is based off of your hopefully accurate glucose reading calibrating it. And even then, it still has a margin of error added to it. So now you have compounding margin of errors.

fgummett · #15 (**permalink**) 01-04-2009, 11:58 AM

The fact is that many thousands of folks with D can and do manage their BG levels successfully with the current level of inaccuracy... we just need to be realistic about the readings we get.

Make sure you test at the same time as you get a fasting BG at the lab to see how good your meter is. If it is way off I suspect that the manufacturer will provide a free replacement - it is the strips where they make their money anyway

Some meters are more sensitive to sample size... for example, the Contour can use a pretty small drop of blood, but I find it best to offer a larger drop and have the strip "syphon off " what it needs rather than trying to "push " a smaller drop blood into it... maybe not the clearest explanation, but technique certainly makes a difference for me.

As for CGMS, I think that the main thing it offers is "the trend"... it's all very well to know what my current BG level is, but is is stable, going up, or going down?