Had bloodwork/tests done for my specialist’s doctor appointment due to the medicine I am on, less than a week later (4 days) had bloodwork/tests done for my primary care provider (PCP) for my yearly physical/wellness check. Different clinics and labs doing the work. Why they couldn’t combine the 2 test to be done at the same time is another question for another time.
My results for the tests came back. Some minor differences between the 2 for some results except for glucose. My glucose reading for my specialist’s appointment was 93 which is well with in the normal/good range of 70-110. My reading for the PCP was 146 which is high. If it makes any difference my A1C was 5.7 on my PCP report.
Why such a difference between the readings? The only differences between the blood draws was the location of the clinic/lab, fasting time between the 2, 10 hours for the PCP and 9 hours for the specialists and the time, 7:30am for the PCP and 3:30pm for the specialists. Shouldn’t make a difference I would think.
Conflicting doctor’s advice, specialist said all my numbers looked very good and keep doing what I am doing. PCP was that I am pre-diabetic and need to make some lifestyle changes. I would like to take the specialist’s advice.
Lab screw up? Would different type of testing would give different readings for the same thing?
That sort of difference in glucose is why doctors usually pay more attention to the A1C and how much that moves over time. Any one blood test can have variable factors on blood sugar that make it not useful for a full diagnosis of diabetes. “Pre-diabetic” only means, after all, that you are at some unspecified non-zero amount of risk for developing diabetes II. Your PCP recommends lifestyle changes to reduce that risk. They won’t get serious unless your A1C starts going up.
If I had two readings like that I would pay some attention to the higher one, and see if making lifestyle changes as suggested (even if they are not as serious as the ones suggested) could make a difference over time.
Stress alone can cause your glucose reading to rise. Also your body can produce more glucose by releasing it from your liver if it thinks you are getting too low. With an A1C of 5.7 I would not be overly concerned with a single fasting blood glucose reading.
Lifestyle changes are always safe advice for a PCP to give.
A lot of people have higher-than-usual fasting blood sugar readings in the morning. There are various reasons, including high carb snacks the night before, insufficient diabetes medication (not an issue for you, I assume)
If your A1C is good, it’s likely not an issue, but it may be worth repeating the test in a couple of months.
as far as combining the blood draws, your specialist and primary care docs would need to coordinate that, but I wouldn’t think that would be a huge issue. Next time around, if you’re going to see the specialist then the PCP a couple weeks later, maybe say to the specialist “hey, can you just give me a written order and I’ll combine that when I see the PCP soon?”.
Some doctor’s offices will not draw blood for an outside order, only their own, so that may or may not work.
Here’s a good summary explaining why lab results can vary. Among other things, labs can use different equipment and analytic processes. There are numerous other variables.
Left unsaid is the possibility that human being(s) may screw up. A personal example is testing years ago that found that my liver enzymes (AST, ALT) were markedly elevated, which given my tendency to assume the worst, must have meant that I had somehow contracted viral hepatitis and was at risk of liver failure. When the test was repeated, all values were within normal limits. Did they initially mix up my specimen with that of another person? There was never a satisfactory explanation for what had happened.
93 versus 146 would seem to be a pretty extreme variance to chalk up to different testing equipment etc (given that in both cases, the OP had been fasting for 9+ hours), though, right? Especially given the A1C of 5.7.
I’d chalk it up to human error, or some other thing causing a transient high reading.
I once had AST / ALT readings through the roof, along with a fasting glucose reading of something like 150 or so, and a lab note that the actual reading may well be higher due to other blood readings (bilirubin, I think). Someone who didn’t know I was in the middle of a rather unpleasant gallbladder attack at the time might have gotten very, very worried (once I passed the gallstone, the readings all normalized).
I also had wildly unusual readings (for me) for my hemoglobin and ferritin levels - but am pretty sure those were triggered by a broken bone a few days earlier.
Lots of things can make readings go wonky for a short time. I tend to think the OP’s high morning reading is due to the phenomena mentioned in that link I posted, but next time you see your primary care doc, discuss it and the timing. If you get another high reading in the morning, try one taken in the afternoon.
That link you posted is fascinating. I always go for labwork fasting, since I do have to have things like my glucose tested. It never occurred to me that doing so would cause skewed results on things like my thyroid levels (I have had other readings that were a titch out of the reference range, and that were chalked up to being slightly dehydrated from… the fasting).
When I went in for my pre-natal diabetes test, which consists of a single blood draw 1 hour after drinking a glucose drink after a 12 hour (overnight) fast, I didn’t expect a problem, other than it possibly coming in low, because I have reactive hypoglycemia, albeit, had not been having symptoms while pregnant.
It came back 178.
So, my doctor had me come back for the full glucose tolerance test-- several blood draws, one an hour, over half a day.
My first one after one hour, was 90-something, and my final one was a little low, though not alarmingly so-- high 60s. They also checked my A1C, and it was fairly low, which it usually is.
Left my OB scratching his head, and said the lab must have screwed up somehow.
I still have no idea what the actual screw-up was.
But because of the hypoglycemia, I test my blood sugar pretty regularly-- every morning, and any time I feel shaky or dizzy. I’ve also periodically tested it 20 minutes after eating when my doctor has requested it. I’ve never had a reading anything like 178. I don’t think I’ve ever had anything over 120.