Tested with 4 meters, same drop of blood

xsquid · #1 (**permalink**) 05-19-2007, 07:38 PM

I squeezed out a big drop of blood and tested it with 4 meters, all new. I was kind of suprised with the results:

Ultrasmart-124
Ultra 2 -140
Ultramini -137
Breeze2 -120

Now it wasn't long after I ate so it wasn't meant as a regular test, just wanted to compare the results. Does the differences sound normal? I was particularly suprised by the differences in the three of the same brand.

AMBlass · #2 (**permalink**) 05-19-2007, 07:54 PM

Those are *very* close readings, there is nothing to be worried about. Meters (even the same meter) have a 15-20% margin of error. According to your numbers, that's approximately 15-25 mg/dl points in either direction!

It's only when your numbers are very spread out, like 357 vs. 281 that you might want to consider getting a new meter or doing some callibration. And having the same brand doesn't mean anything. Every meter is different.

Who? · #3 (**permalink**) 05-19-2007, 08:21 PM

Do the three of the same brand use the same strips?

JediSkipdogg · #4 (**permalink**) 05-19-2007, 08:28 PM

Quote:

Originally Posted by Who?

Do the three of the same brand use the same strips?

Yes....the entire Ultra line uses the same strip.

Here is a small study I did comparing 4 popular meters a while back. I tested 25 times with using 4 meters and a very large drop of blood. The results may astound you at times.

Blood Glucose Meter Comparison

xsquid · #5 (**permalink**) 05-19-2007, 08:51 PM

OK amblass, thanks.

Very nice post jedi, thanks.

nneighbour · #6 (**permalink**) 05-19-2007, 09:11 PM

You're at 15% difference between highest and lowest. So it's not bad. The real test is the difference in results between two tests on the same meter.

xsquid · #7 (**permalink**) 05-19-2007, 09:16 PM

Maybe I'll do that on the same 4 meters tomorrow.

Harold · #8 (**permalink**) 05-19-2007, 10:10 PM

Quote:

Originally Posted by xsquid

I squeezed out a big drop of blood and tested it with 4 meters, all new. I was kind of suprised with the results:

Ultrasmart-124
Ultra 2 -140
Ultramini -137
Breeze2 -120

Now it wasn't long after I ate so it wasn't meant as a regular test, just wanted to compare the results. Does the differences sound normal? I was particularly suprised by the differences in the three of the same brand.

Splitting the difference between the high and low would give a 130 value, and between the 3 Ultras a 132. Which would mean that all four meters did better than 10%. That's pretty good, so don't beat your self up over fruitless testing. It's a waste of money!

someone · #9 (**permalink**) 05-19-2007, 10:26 PM

I notice the exact same thing with the UltraSmart and Ultra 2. The thing is, I can test twice on the UltraSmart and twice on the Ultra2, and both will give close to the same readings as they did the first time. I also might mention that I used the same box of strips to test them out.

For this reason, I have decided to just stick with the UltraSmart. I picked the UltraSmart because its readings are closer to what I get from the BD logic. Glad to hear I'm not the only one that noticed this.

To those that say these differences are not a problem, it is a big problem when you wear a CGMS. When calibrating, 20 points is a very big difference. Usually when I calibrate, my BG meter is only 5-10 points different from my CGMS.

xsquid · #10 (**permalink**) 05-20-2007, 01:19 AM

Quote:

Originally Posted by Harold

Splitting the difference between the high and low would give a 130 value, and between the 3 Ultras a 132. Which would mean that all four meters did better than 10%. That's pretty good, so don't beat your self up over fruitless testing. It's a waste of money!

That would be correct if 130 or 132 was the correct value, but if for example the breeze 2 was dead on the ultra 2 would be 20 points off or vice versa. If 20 points difference is acceptable I can live with that, but I really don't know which is the closest to being on target and which ones the furthest off. I mistakedly assumed tests on the same brand meters with the same test strips on the same drop of blood would be closer than they are, live and learn I guess.

caswellhb · #11 (**permalink**) 05-20-2007, 02:47 AM

Had you done control tests on all of them first?

Heather.

xsquid · #12 (**permalink**) 05-20-2007, 11:00 AM

Yes, on all of them.

Who? · #13 (**permalink**) 05-20-2007, 11:26 AM

Squid;

Does the dispersion of the blood drop readings follow that of the control solution tests? If so, then I guess it would be safe to assume that whichever one was closest on the control is the most accurate.

Is the order you listed the meters in the order in which they sampled the drop? I am sure that the drop was changing its characteristics second by second between evaporation, clotting and who knows what.

xsquid · #14 (**permalink**) 05-20-2007, 12:12 PM

I plugged the strips in all of them, then got the large drop so they were all ready. It only took me a few seconds to test all of them so the blood should not have changed much.

The order I posted them is not necessarily in the order I tested.

I'm not sure what you mean by the closest on the control since the control is a wide range. Maybe I'm just dense.

Who? · #15 (**permalink**) 05-20-2007, 12:47 PM

Yes, the control is a range, but the middle of that range is the "true" value which the strips should read if they are coded correctly and the meter is not bad. So take the middle of each control range and compare each meter to that, then, as I say, I would pick the closest one(s).

The range on the control solution label is just the mean ("true value") plus and minus whatever the tolerance is that the manufacturer allows. It is usually 20 mg/dl below 100 and 20% above or less.