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Medical Forum / Diseases and Disorders / Diabetes / March 2006Meter Data versus Blood Test Data
I just had a blood test today at a ab. Right afterward I used my meter to get the glucose results as well. Next week I will get the results of the real lab test. What should I expect? How close is the result of a lab test to the "meter at home" test? The funny thing is that I woke up with a 91 but had a 110 after the test 2 hours later (around 9 am). If I don't eat, which they ask you not to for the test, my number keeps going up as time marches on. So I usually have some B'fast which will keep my numbers in check, more or less. Also, I asked to have my A1C checked. It has been about 7 weeks since diagnosis. At the time, my A1C was 12! I take it that that is a real bad number as I should be under 7.0. Now, how much can I expect it to come down over 7 weeks? I was told, by not a real good source, that A1C is like a 30 day average type of number ( I don't have a good grip on this test yet). My last 30 days I averaged 126 and 112 for past 14 days. I have been totally off insulin for 4 weeks, started 3 times per day and dropped dose and doseages over first 2.5 - 3 weeks. So, will my A1C improve in a significant way or should I just figure that I obsessed with fixing myself quick and let things settle for a longer period of time? If BG is constant, what level of BG equates to what A1C result? For example: BG A1C 600 12 500 11 400 10 300 9 ....etc. Is there an approximate correlation? And, being the nut I am, I had them check my cholesterol again. During the test that diagnosed me my numbers were all whacked out. Every number was way out of range. Should I expect a more normal result this time? Anxiety is one of my strongest traits! Bet you couldn't have guessed! Thanks for the info, Sax > I just had a blood test today at a ab. Right afterward I used my meter to > get the glucose results as well. Next week I will get the results of the > real lab test. What should I expect? How close is the result of a lab test > to the "meter at home" test? My meter is usually within 5 mg/dl of the lab except for the one time when it was 50 mg/dl off--which was when I tossed it and got a new one. <snip> At the time, my A1C was 12! I take it that that is a real bad > number as I should be under 7.0. Now, how much can I expect it to come down > over 7 weeks? It is too early to do an A1c. Typically, the A1c reflects the last 3 months of blood sugar control with a heavier impact from the past month than from the first two, but they still have an effect. I've also noted that if something pushes my blood sugar WAY up for only a day or two it can still push the A1c up much higher than my daily measurements would suggest. > If BG is constant, what level of BG equates to what A1C result? There are some formulas which have been derived from large studies. Very roughly 5.0% = average blood glucose of 100 mg/dl. 6.0% = " " " " 136 mg/dl. 7.0% = " " " " 171 mg/dl 8.0% = " " " " 207 mg/dl So it is roughly 36 mg/dl per percentage. But there is plenty of variation between individuals, because what the test is really measuring is how much glucose is stuck to your hemoglobin molecules, and depending on the nature of your hemoglobin, that may or may not be an excellent index of how high your blood sugar has been running. > And, being the nut I am, I had them check my cholesterol again. During the > test that diagnosed me my numbers were all whacked out. Every number was > way out of range. Should I expect a more normal result this time? Probably not. It can take six months or more for total cholesterol to come down if you improve your diet, especially if you are losing weight. Weight loss can cause LDL to go up for a while. Your triglycerides, OTOH, should start improving as a result of your enormous improvement in blood sugar control. > Anxiety is one of my strongest traits! Bet you couldn't have guessed! > Thanks for the info, Anxiety is the diabetic's friend. Consider it a gift. <G>  Signature--Jenny http://www.phlaunt.com/diabetes Diabetes Info http://www.alt-support-diabetes.org/newlydiagnosed.htm Get Your Blood Sugar Under Control Saxology says... > I just had a blood test today at a ab. Right afterward > I used my meter to get the glucose results as well. > Next week I will get the results of the real lab test. > What should I expect? How close is the result of a lab > test to the "meter at home" test? When I tried that, the lab got 108 on the venous blood draw, and my meter (Relion) said 91 on a finger-stick sample one minute later. I didn't think that was close enough. Next time, I'll get them to let me test my meter from a drop of venous blood in addition to doing the regular finger-stick. That should tell me whether the difference is caused by the meter, or just a lower glucose content in the capillary blood. Actually, I don't really need to know that, since it doesn't matter so long as the difference is consistent, but I'm just curious about it. One other thing I've wondered about - if you do two tests in succession, you often get different results. Could that be because heat produced within the meter during the first test changes the characteristics of the electronic components enough to change its performance on the second one? In fact, I wonder if they've ever tested the effect of temperature of the meter, strips, or blood on the readings. > One other thing I've wondered about - if you do two tests in > succession, you often get different results. Could that be > because heat produced within the meter during the first test > changes the characteristics of the electronic components > enough to change its performance on the second one? Which way did the readings go. I'll bet there are more variables outside the meter than the in the meter for a given test. > In fact, I wonder if they've ever tested the effect of > temperature of the meter, strips, or blood on the readings. I believe temperature at the end of test strip makes a big difference. Cold fingers give a much lower reading than warm/hot fingers. Warm test strip gives higher reading than cool test strip. For me, I had a difference of 12 for cool/warm fingers and 21 for cool/warm strip. It points out to me, I have to take the sample the same way every time to get a consentant reading. Warm fingers, load test strip, create blood drop same size, feed strip same way. Bit Twister says... >> One other thing I've wondered about - if you do two >> tests in succession, you often get different results. >> Could that be because heat produced within the meter >> during the first test changes the characteristics of >> the electronic components enough to change its >> performance on the second one? > Which way did the readings go. I'll bet there are more > variables outside the meter than the in the meter for a > given test. Higher on the second test. > I believe temperature at the end of test strip makes a > big difference. > Cold fingers give a much lower reading than warm/hot > fingers. > Warm test strip gives higher reading than cool test > strip. The problem is the inherent variability of the test itself. I'll bet if you did tests using standard solutions, with temperature controlled, you'd still get different results. I think the problem there is with the strips. It's an electro-chemical reaction of some kind, and it's probably impossible to make all the strips react the same, even within a batch. Well, it should be possible to do a kind of controlled trial to see if your assertions are correct. You could heat one finger and cool another one, then test both. Then do it all again testing in the opposite order. That kind of thing. I wish I understood the technical side of how these meters work - exactly what is measured. I've never seen that described anywhere. > It points out to me, I have to take the sample the same > way every time to get a consentant reading. Warm > fingers, load test strip, create blood drop same size, > feed strip same way. It may be that large drops produce higher readings, but that could be explained by the cooling effect while squeezing for a small drop and waiting for enough blood to collect to do the test. Well, either we're full of it, or the meter manufacturers should have done these tests and given guidelines. Or, you know, the ADA should have, or Consumer Reports. > The problem is the inherent variability of the test itself. > I'll bet if you did tests using standard solutions, with > temperature controlled, you'd still get different results. I can believe that with your test setup. If I wanted to test the meter, I would just kludge up a strip to have a fixed restance which not vary much with temperature. Then you can trust the meter swing versus on/off time. > I think the problem there is with the strips. It's an > electro-chemical reaction of some kind, and it's probably > impossible to make all the strips react the same, even > within a batch. Agree, but under those conditions, I would bet you would be back in the 10% range. > Well, it should be possible to do a kind of controlled trial > to see if your assertions are correct. You could heat > one finger and cool another one, then test both. Then do it > all again testing in the opposite order. That kind of > thing. Or cool finger, test, hot water to warm, test same finger, cold water, test same finger. > I wish I understood the technical side of how these meters > work - exactly what is measured. I've never seen that > described anywhere. True. Having some electronics training. I can guess a value given to a analog to digital converter which is read by the meter. Now the amount of current flowing in the strip will depend on how much blood is in the strip and resistance will depend on temperature and as you suggest, chemical reaction in the strip. > It may be that large drops produce higher readings, but that could > be explained by the cooling effect while squeezing for a small drop > and waiting for enough blood to collect to do the test. I was thinking of the strip having a thin film of blood (lower reading, small drop) instead of filling the little window full (higher reading, larger drop). > Well, either we're full of it, or the meter manufacturers > should have done these tests and given guidelines. Or, you > know, the ADA should have, or Consumer Reports. I can see where the meter manufacturers want to leave wiggle room for the lawyers. :) How would the manufacturer indicate a finger temp for the average user and how would the user get that reading. :( For my warm strip test, I poped two strips out of the foil. I ran fingers under hot water, dried them, held tip of strip between index/thumb to warm strip. I did take care to not squeez hard in order to not change the little test window size. Then drew blood for each test same finger. For the people using the mmol/l values they would not notice much swing in values. For us using mg/dl, the swings look large. All you can do is, run your tests keeping the variables constant as possible. Get a reading off your meter as soon as possible after venous blood draw to get a delta between your readings and lab results. > Saxology says... > [quoted text clipped - 23 lines] > fact, I wonder if they've ever tested the effect of > temperature of the meter, strips, or blood on the readings. I just talked to my meter company about that....as I had a question about the different readings between my 2 meters of their brand. I wanted to see if the meters would read the same with the same finger stick blood. She told me that each drop of blood has a different glucose level. I do not know if that is true or not, but sounded plausible to me. Suzi A1c 6.4 T2 DX 10/2002 Glucophage 2 x 1000mg Lipitor 20mg (3 days a week), Enalapril 20mg > I just talked to my meter company about that....as I had a > question about the different readings between my 2 meters of > their brand. I wanted to see if the meters would read the same > with the same finger stick blood. She told me that each drop of > blood has a different glucose level. I do not know if that is > true or not, but sounded plausible to me. I think it is part of the line of crap that the customer service people at meter companies are trained to give out. When my Aviva meter was testing 49 points higher than the lab, and 30 points higher than another model sold by the same company, they gave me a whole line of B-S to excuse it too, starting with was my meter too close to a sink or had I squeezed the finger too hard, etc, etc. When I pointed out that the other meter they sold worked just fine and matched the lab, they ended up retreating to the argument that their meters only had to be plus or minus 10% accurate. Then they sent me a new meter. <g> My Ultra is consistent within about 5 mg/dl with itself or with the backup Ultra I just bought to keep in my purse so I'll stop forgetting to take it). --Jenny http://www.phlaunt.com/diabetes Diabetes Info http://www.alt-support-diabetes.org/newlydiagnosed.htm Get Your Blood Sugar Under Control > > I just talked to my meter company about that....as I had a > > question about the different readings between my 2 meters of [quoted text clipped - 26 lines] > http://www.alt-support-diabetes.org/newlydiagnosed.htm Get Your Blood > Sugar Under Control The reason I called was that when I tested on my Ultra Smart it read one thing then tested on my backup Ultra it tested 20 points higher. Would have tested on my second backup (a Q.I.D.) but didn't have any strips for it. One touch says theirs are accurate within 20%. I am trying to figure out why I am so out of whack lately. Waking up high and having a heck of a time staying down throughtout the day. Woke up this morning with a 172, went to bed with a 109. Suzi A1c 6.4 T2 DX 10/2002 Glucophage 2 x 1000mg Lipitor 20mg (3 days a week), Enalapril 20mg > The reason I called was that when I tested on my Ultra Smart it > read one thing then tested on my backup Ultra it tested 20 points [quoted text clipped - 4 lines] > throughtout the day. Woke up this morning with a 172, went to bed > with a 109. How old are your meters? Also, if you've had them for a while, have you changed the batteries? Have you taken the meters out into the cold? I had a meter that was rock solid accurate (compared to lab several times) which started reading far higher when I took it out and left it in the car in the cold. I'm guessing now that the battery got drained though at the time I didn't realize that was the case. That meter was 70 mg/dl over the lab when I compared. Another customer service person told me that after 2 years the meters can get fluky. Ultra was doing the "buy a meter for $30 and get a $30 rebate" thing last week at Walgreen's, so I picked up a second one to keep in my purse. Maybe you should look for a deal like that and get a new meter. Barring that, replace the batteries. . . . --Jenny http://www.phlaunt.com/diabetes Diabetes Info http://www.alt-support-diabetes.org/newlydiagnosed.htm Get Your Blood Sugar Under Control > > The reason I called was that when I tested on my Ultra Smart it > > read one thing then tested on my backup Ultra it tested 20 points [quoted text clipped - 31 lines] > http://www.alt-support-diabetes.org/newlydiagnosed.htm Get Your Blood > Sugar Under Control My Ultra Smart is only about 6 months old. Got it for free with a coupon, my backup Ultra I got when dx in 10/2002. So maybe need new batteries for it. Yes, my meters do go out in the cold, I do live in Colorado and after a few weeks of spring weather got hit with 3 days of snow. I do current have a free coupon for the new version of Precision Xtra meter just waiting for the store to get it in. Once I make it down to the county health department and get a denial letter from Medicaid then I can get a free Freestyle and stripes as long as I stay qualified. Suzi A1c 6.4 T2 DX 10/2002 Glucophage 2 x 1000mg Lipitor 20mg (3 days a week), Enalapril 20mg > My Ultra Smart is only about 6 months old. Got it for free with a > coupon, my backup Ultra I got when dx in 10/2002. So maybe need > new batteries for it. You buy them in the Watch Battery section. They aren't that expensive. That would be my first suggestion for what to do. Yes, my meters do go out in the cold, I do > live in Colorado and after a few weeks of spring weather got hit > with 3 days of snow. Definitely try the new battery! I do current have a free coupon for the new > version of Precision Xtra meter just waiting for the store to get > it in. I have one of those as a backup, since the strips are cheaper, but it is a bit too all over the place. The Ultra seems like a more consistent meter. --Jenny http://www.phlaunt.com/diabetes Diabetes Info http://www.alt-support-diabetes.org/newlydiagnosed.htm Get Your Blood Sugar Under Control > > My Ultra Smart is only about 6 months old. Got it for free with a > > coupon, my backup Ultra I got when dx in 10/2002. So maybe need [quoted text clipped - 22 lines] > http://www.alt-support-diabetes.org/newlydiagnosed.htm Get Your Blood > Sugar Under Control That is what I have heard about the Ultra's. I will look into a battery for the Ultra. Luckily the Ultra Smart uses 2 AAA's. Suzi A1c 6.4 T2 DX 10/2002 Glucophage 2 x 1000mg Lipitor 20mg (3 days a week), Enalapril 20mg >> My Ultra Smart is only about 6 months old. Got it for free with a >> coupon, my backup Ultra I got when dx in 10/2002. So maybe need >> new batteries for it. > >You buy them in the Watch Battery section. They aren't that expensive. >That would be my first suggestion for what to do. Hi Suzi, via Jenny Over here I ring Accu-check (Roche) and they mail them to me free. It may be worth a try to dial your meter manufacturer's free-call number and ask for help. Cheers, Alan, T2, Australia. d&e, metformin 2x500mg SignatureEverything in Moderation - Except Laughter. > >> My Ultra Smart is only about 6 months old. Got it for free with a > >> coupon, my backup Ultra I got when dx in 10/2002. So maybe need [quoted text clipped - 11 lines] > Cheers, Alan, T2, Australia. > d&e, metformin 2x500mg I think that they offered to send me a new one, but I told them as of right now I would declined a new one. Gonna try the new batteries and see how it goes. SignatureSuzi A1c 6.4 T2 DX 10/2002 Glucophage 2 x 1000mg Lipitor 20mg (3 days a week), Enalapril 20mg 30 minutes walks 7 days a week > Saxology says... > [quoted text clipped - 23 lines] > fact, I wonder if they've ever tested the effect of > temperature of the meter, strips, or blood on the readings. The documentation that came with my One Touch Ultra says +/- 3 My experience is temperature does effect meter readings, especially cold mornings. ======= Tecknomage ======= San Diego, CA The Mage Soapbox http://magesoapbox.blogspot.com/ Tecknomage says... > The documentation that came with my One Touch Ultra says > +/- 3 That's pretty good. > My experience is temperature does effect meter readings, > especially cold mornings. Temperature of - hands, meter, strips? And I assume cooler means lower readings. > Tecknomage says... > [quoted text clipped - 8 lines] > Temperature of - hands, meter, strips? And I assume cooler > means lower readings. For my ReliOn meter at 70 degrees room temp, difference was 12 hands and 21 strip (mg/dl) and yes, cooler had the lower value. On Tue, 14 Mar 2006 07:48:47 -0600, Peabody <waybackKILLSPAM44@yahoo.com> Huffed and Puffed the following into the madness of usenet: >Tecknomage says... > [quoted text clipped - 8 lines] >Temperature of - hands, meter, strips? And I assume cooler >means lower readings. all three. each with it's own problems. cold hands, hard to get samples. cold meter, may not even operate correctly if at all until warmed up. cold strips, if actually dry shouldn't be a problem, however if the cold causes condensation of moisture on the strips it can skew the results. Happens mostly when testing outside, or coming in from the cold to a heated humidified house. SignatureMâck©® Deltec CoZmore Pumper Type 1 since 1975 http://www.alt-support-diabetes.org http://www.diabetic-talk.org http://www.insulin-pumpers.org "To announce that there must be no criticism of the President, or that we are to stand by the President right or wrong, is not only unpatriotic and servile, but is morally treasonable to the American public." ...Theodore Roosevelt (o ô) --ooO-(_)-Ooo-------------------- "I don't know half of you half as well as I should like; and I like less than half of you half as well as you deserve." ....Bilbo Baggins Jesus never hated anyone. [[ This message was both posted and mailed: see the "To," "Cc," and "Newsgroups" headers for details. ]] > I just had a blood test today at a ab. Right afterward I used my meter to > get the glucose results as well. Next week I will get the results of the > real lab test. What should I expect? How close is the result of a lab test > to the "meter at home" test? For whatever it is worth, and as a data point for you, with the meter I trust the most, a One Touch Ultra, I got meter readings .5 mmol/L below the first lab result and .5 mmol/L above in the next lab result. (The blue line in this graph http://www.geocities.com/john.101a/image003.png is the One Touch.) Simultaneously I've also used two BD Logic meters. They read high and erratic. The readings on the chart are from the same drop of blood using two or three meters. Red is the BD Logic meter #1, Yellow is BD Logic meter #2. BD Logic meter #1 read 7.7 when the lab read 6.1. DX Oct 2005, T2, Glyburide x2 2.5mg |
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