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Potentially defective blood glucose monitor? Opinions

rickydoo

Member
Messages
23
Hello! A month ago I was diagnosed with type 2 diabetes and have managed to keep my blood glucose numbers in the range my endocrinologist and primary doctor asked me to keep them in(less than 7.2mmol/L in the morning and less than 10mmol/L after meals). A week and a half ago my endocrinologist put a continuous blood glucose monitor on me and after tracking my numbers for 3 days told me I could get off my 1 a day 500mg metformin pill as long as I kept my numbers looking good! Initially after discontinuing the metformin I noticed a small spike in my numbers but nothing out of my recommended ranges. A couple days ago I ate a meal that would’ve spiked my numbers way more two weeks ago and yesterday I had a large burrito on white tortilla with some rice in it and after checking my blood sugar an hour later it was only at 5.3mmol. Today I ate bowl of cereal in the afternoon with whole milk, and a footlong Italian sandwich on wheat in the evening, I check my numbers an hour after the sandwich and I’m at 5.0mmol/L. An hour later my gf’s roommate offers me a large homemade pizza made with flour, I eat it, measure my blood sugar and it reads 4.9mmol/L 40 minutes later! My gf says I should be grateful my numbers are so good but I’m kinda worried my monitor is defective and my blood glucose is actually really high! What are your thoughts on this? sorry for the long post guys
 
Well taking one-off readings at pretty random times after meals won’t catch any spike, or it’s duration so I’d say there’s neither grounds for saying you didn’t have spikes after eating those foods or for saying the meter is defective.

It’s pretty unlikely the meter is defective - you could try the control solution if you have any but I’d suggest that looking at how and when you test might be a more productive strategy.
 
Agree with @Goonergal pretty unlikely it is defective but your timing of testing may not be telling the real story

For testing meals usually test before your first bite and then 2 hours later. Its great that you are off your meds and your numbers have improved.
 
Yeah agreed, the timing might possibly be hiding the actual spike. Sone foods I eat, like carb laden wise when I don’t have a good day spike me later and for longer. It’s possible the hour after eating hasn’t caused the rise yet

2 hour mark I think is the likely peak, so as others have said, test then. But it’s most people so not always going to be the full picture (CGM however will give more of a view)
 
From (unfortunate) first hand experience, fatty carby foods can delay the spike for hours after the meal. Admittedly, am a T1, so this may not be relevant to T2s, but I thought I'd put it out there.

What was your hba1c at initial diagnosis? Any chance that that could have been an error? Have you done anything to improve your insulin sensitivity since diagnosis? Weight loss, more exercise? If your improvement is because of carb reduction then I suspect that returning to old eating styles may soon return you to diagnosis levels of blood sugars.
 

My A1c was 7.5. I’ve lost more than 10 pounds in the last month and I’ve been working out yes and I’ve limited my carbs drastically. The past couple days I’ve been eating a bit more “poorly”(for lack of a better word), but it’s just me experimenting with my body(I know I shouldn’t) I’m still low carb for the day, and haven’t gone over my numbers! Also just woke up took my numbers and I’m at 5.0 mmol.
 
Your post is very valid, at least for this particular T2

fish and chips last night. Unfortunately don’t know exactly immediately prior to eating but:

  • 7.3 @ 1314
  • 1715 food of a huge piece of battered plaice and a fair few chips…. didn’t record oops but expect around 5 given my usual reactions
  • 5.6 @ 1915 (weird… Note 2 hours after eating and I did 30mins cardio)
  • 8.7 @ 2145 (so no extra food but still climbing)
  • 7.1 @ 0527 (Note I am normally low 5 if not high 4)
  • 0617 ate avacado and cheese
  • 5.6 @ 0817
So highly unscientific but it appears the spike from my fatty carbs was later and a lot longer than you would expect, causing an increase well past the 2 hour point and into the day after
 
As I understand it @rickydoo was wearing a CGM during this food fest, so any rises and spikes should be clearly visible whenever readings were taken.
 
becca59 said:
As I understand it @rickydoo was wearing a CGM during this food fest, so any rises and spikes should be clearly visible whenever readings were taken.
Click to expand...

Without wanting to derail, the OP reads that there were 3 days using a CGM, after which metformin was discontinued. The ‘experiment’ with these foods was subsequent to that and the thread title is about a potentially defective meter. I’m sure @rickydoo can advise.
 
rickydoo said:
My gf says I should be grateful my numbers are so good but I’m kinda worried my monitor is defective and my blood glucose is actually really high! What are your thoughts on this? sorry for the long post guys
Click to expand...

My thoughts are that if your monitor was accurate when it was giving you higher readings previously then it's most likely accurate now.
 

The cgm was not used recently. Just a finger prick monitor. I’ve come to the the conclusion that I’m probably just not catching my spikes.
 
I agree with previous posters that you may not be catching your spike. So many things can effect it. If I have something more carbs than usual- which I haven't for a long while I used to test every 30 mins to work out when the spike was. Yes I know I'm a bit (okay a lot) obsessive but it was a real education for me and how my body reacts. I don't do it anymore as I don't eat many carbs at all.

take care of yourself- you don't want to undo the progress you have made.
 
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