Test Results

[Windbreaker]

I am new to this and wanted to draw on the experience of the great people who volunteer to answer our questions.  My question is:  Is there usually a difference in the test results from blood drawn from the arm and blood drawn from the finger tip?  I heard that the fingertip blood can test higher than blood drawn from the arm and I wondered if that is usually the case.

Thanks, Jerry

[JDRF-Team-BL]

Dear Windbreaker,
    There is a difference between the blood drawn from a vein in the arm and that from capillaries in the fingertip. It usually isn't so difference to cause a bad reading that home blood glucose testing process should be not done. i have been diabetic over 30 years now and the home finger testing of blood is so much better than it used to be. When i first became diabetic all they had was urine testing, which sugar only shows up in the urine if the blood sugar goes above 180, which they'd shoot you now for going that high. i even have an antique book from 1929 published by the Joslin Clinic about diabetes and in the front faceplate they show the colors you compare the urine test to for a reading, back then you even had to boil the water and chemicals together to get your result which meant no testing when not at home. Diabetes care has progressed rather nicely, in that complications don't show up so soon and diabetics live  much longer now. So don't be worried about home blood sugar tests. Good luck, bret

[Windbreaker]

Thanks Bret for your answer.  Is the test done from blood drawn from the arm usually lower or higher than the test from blood drawn from the finger?  Thanks,  Jerry

[JDRF-Team-LRS]

Hi again,
Here's a comment I posted a while back when a similar question was asked, I've changed it a bit, but the msg is the same.  Hope it's helpful.

I'm not a physician, but a long-time diabetic. Do verify our info with your doctor, too.

Our home meters that test blood we take from capillaries are expected to be a good basis by which to treat our diabetes on a daily basis. A good way to see if yours is within normal variance is to bring along your meter when you go for a blood draw (from a vein). Within 5-10 minutes of them drawing blood, do your own blood test and save the results. Compare them with what the doc tells you your number was.

Your result should be within 15% of the doc's result.

What's important here is to know how you feel & how you function when your BG is at different numbers. Of course, 100 isn't much different from 115 or 85 (we likely feel good - and all numbers are within a good range). And 300 isn't much different from 345 or 255 (we likely feel lousy - and all numbers are waaay too high). However, 70 might feel quite different from 60 or 80, so if I'm feeling low and my meter says 70, I treat it like a low and get on with my life.

I'm not sure there's a sure "direction of difference" since part of the difference is due to the time lag between blood in our veins and blood in our capillaries.  If I understand the mechanism right, it takes a while for blood to get into the capillaries, so the difference between vein & capillary BG readings might depend on the direction of BG change and the rate of that change we might be experiencing.