Today I had an opportunity to compare my current meter (Accu-Chek Guide that I have been using for about 2 years now) to a venous blood draw at the Lab.
Because I was getting some fasting tests done after a 12 hour Fast I knew that in the hour between me testing at home and letting the Vampires suck it out of my arm the difference should not be significant.
So I tested my blood like normal at 6:28 AM - first thing I do after crawling out of bed in the morning and then I had a blood draw done… read more
@A DiabetesTeam Member that has something to do with a couple of factors.
First it takes time for the sugar to (migrate) from our veins (venous blood) to the capillaries (where we get out stick test blood) then to the fluid around the cells which they feed from.
So we are (home) testing that blood as it is passing from where it's going to from where it's coming from. No problem if everything is stable but if we are in a state of rising or falling blood sugar then in all three (places) the sugar levels will be different.
They can also be "a little different" from one finger to the next because of longer or shorter capillaries being fed by the same vein, slightly different circulation - even something as seemingly insignificant as a longer compared to a shorter finger.
That is why Venous blood is the most reliable and CGM reading (from cell fluid) are the least (and slowest to reflect what real blood sugar is at any given moment).
Plus, the sugar you are measuring in the capillary is moving to "feed the cells". If they are "really hungry" it's pulling it through "quicker" which means even as little as minute later can result in a higher or lower number (but relative - we get hung up on single points when really a 10 point difference is like a rounding error for blood sugar).
That's why Type 2 is treated on "averages" and not single points of reference - it all comes out in the wash if you average 20 fasting numbers - sometimes they will "really be" lower than venous blood and sometimes higher. But "on average" you will get a number reliable enough to make treatment decisions.
@A DiabetesTeam Member I do work with an educator group (some members here are aware).
I'm the "token diabetic" in a group of 4 that includes a Pharmacist, Dietitian and Counsellor (those three are CDE - Certified Diabetes Educators).
We "take the show" to workplaces under a "wellness in the workplace" program. The employer just needs to provide a place for the presentation and they get a kickback for letting the employees attend the 1 or 2 hour session while getting paid during the workday.
So some of what I know is because I'm a 4th generation Type 2 and have been sitting in doctors offices with a parent or grandparent (sometimes an aunt who needed a ride etc) since the 1960's.
But the other part is because I have been (present) in dozens of presentations from the pro's - and we have a couple different levels of the class - one for "what the heck is diabetes", how to use a meter or give an injection up to a module for "veterans" that are looking to take a more active role, discussions on the treatments.
It is my (personal) dietitian that got me involved. We were having a decent discussion one and she asked if I would tag along to a particular group because they often got the comment "you don't have diabetes so don't understand" and asked if I would give my (story and perspective) as a controlled diabetic not on meds and it kinda expanded for me from there to the point where I have my own presentation as part of the group.
What we were thaught as nurses, was to rub the finger before poking it, so the red blood cells do not burst and cause false readings (rubbing after poking the blood cell can burst. Not sure how much of it is true, but I too have in the past tested with same finger stick on 3 different machines. The most accurate was my Libre reader as I had brought it with me and the nurse told me to check right after she drew the blood, and once I would have the results I could verify. So this is why I used my Libre reader as a glucometer. The other machines we have here reads a good 0.5 to 1.0 above. EverytimeI go for yearly blood tests I make sure i have a Libre on and bring my Libre reader also and check with blood stick.
@A DiabetesTeam Member explained it quite well about the capillaries and larger blood vessels being different results due to cells absorbing some sugar along the way. The blood sugar levels in blood taking in the arm will be the most accurate as most of the sugar got absorbed along the way back to the heart. Sometimes in ICU we could not get blood drawn from arms, so we used central lines in jugular veins, which were even closer to the heart and those results at times differed from finger sticks on patients which we could get finger sticks on, we often checked the finger sticks and compared with blood drawing samples as health care workers and yes there is a difference between the 2 readings. Sometimes we would do finger sticks and if the results were not usual for that patient or did not register on the meter, we would send blood sample from veins and got more accurate readings this way.
Sometimes people's finger sticks blood samples clotted more quickly and might give out a false reading due to the clotting. This is also true if you poke yourself and do not get enough blood and try and milk more out, the red blood cells get destroyed when this is done and readings will not be accurate. It is best to use another needle and site and rub before poking or warm the finger under warm running water to get a better size sample. Milking the site after poking trying to push more blood out is never a good idea.
Do you know what is funny? When we forget to swab our fingers before testing. If your fingers are not clean before testing, then your readings will be off. Also, let's talk about changing finger poke needles. Hello people! I know we all get tired and may just think "Oh it's just me! I don't need to change my blood testing needle poker." Umm..
While maybe short term it won't mess with your numbers..but having a clean needle each stab helps us get the best results. Besides even poking needles get blunt and you want to be sure you get a poke where enough blood comes.
I lower my arms to my side and shake my hands a few times. Seems to help the blood flow in my fingers.