I have a cat who is borderline diabetic. So, I do a blood glucose on her every other day. I use one of the off the shelf glucose meters and give her insulin adjusting the dose depending upon her levels. One day her little ear prick produced a large drop of blood and on the same drop of blood I got three tests and three completely different readings of 127, 144 and 181. Now if I have a large drop of blood on her I try to get multiple glucoses on her. Subsequently I have obtained results from a single drop of blood two readings of 134 and 168. For the science geeks out there 100 is normal and the units are mg/dl which is equal to about 4 mM.
Part of my work is concerning bedside diagnostic devices in medicine; called point of care, and we regularly work with similar device concepts as the glucose meter. I have seen companies and experts in the filed talk about error and failure rates on these devices of 15 to 20 percent. So if on the 3 sample day the true value was 150 the differences would still be in that plus or minus 20 percent range. But is that what we should tolerate? I make insulin dosing decisions based on those answers. Part of me thought it was interesting to see how those errors look from the other side of the point of care fence but another part of me was extremely frustrated because I’m not sure I can trust the results to make dosing decisions.
I feel anxious as to how to best care for my cat. I’ve seen what happens when she gets overdosed on insulin (accidentally and it knots my stomach just thinking about those two horrible days) so I really need to trust the glucose results before giving her insulin. Believe me the glucose meter I purchased is sold to humans with diabetes who need to make those same insulin dosing decisions. When they overdose on the insulin it is their brain who gets starved of glucose and they can suffer greatly. So, why are we putting up with a lack of precision in these devices of 20%? Moreover, do patients and caregivers who make insulin dosing decisions realize how much error there is behind those numbers? Should we all do 3 tests and hope the average is closer to correct?
To tell you the truth, I do not know the answers to any of those questions. But I can tell you that in my research we are trying very hard to minimize the error and maximize the precision and accuracy of what we are developing. I do not want to be the cause of some physicians’ or care givers’ angst when trying to make treatment decisions based on the diagnostic products and answers my research yields. I learned part of the importance of my research by testing my cat’s glucose. My little insulin dependent kitty is named Clawdia, she is 17 years old and this teenager has taught me an important lesson. Thanks Clawdia.
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The following is reprinted anonymously with permission.
We deal with it in the field too. I double or triple test patients before we give them D50. Anything under 70 is double checked. Anything under 60 is triple checked. Over 250 is double. Over 350 triple. The brand of glucometer we use just reads ‘low’ under 20. or ‘high’ over 500. We’ve tested hypoglycemics and gotten a ‘low’ reading multiple times only to have the hospital get a WNL reading. I personally clean and calibrate our glucometer weekly because of the excessive use.
A faulty reading on a diabetic resulted in his death. his wife said he was feeling bad and his blood sugar was really high so she dosed him with his nightly 90 units of insulin. He fell to the ground right after she dosed him; cardiac arrest. (not a save) even with an amp of D50 pushed along with the first line cardiac meds, his blood sugar was too low for a reading.
February 23, 2010 @ 12:09 am
I am Type 2 diabetic, and use a meter for dosing. I use an Accucheck Advantage, and as a Ph.D. biochemist specializing in new assay techniques, the first thing I did was test it for accuracy, There are test solutions sold by the meter companies, and I always keep them around. My meter, thankfully, was very accurate, both from multiple readings from the same blood drop, and between blood drops from different locations at the same time.
However, 99% of Type 2 diabetics are not going to have my experience or knowledge, and calculating insulin dose based on the your current sugar and meal you are about to eat is not simple even for me, when I am hungry!
March 3, 2010 @ 4:51 pm