Different CGM's rank meals differently

Eddy Edson

Well-Known Member
Relationship to Diabetes
Type 2
Imprecision nutrition? Different simultaneous continuous glucose monitors provide discordant meal rankings for incremental postprandial glucose in subjects without diabetes



Conclusions
Precision nutrition approaches that use CGMs to personalize meal recommendations for minimizing glycemic excursions may be premature given the discordance of within-subject meal rankings between simultaneous CGM devices. More research is needed to clarify the source of this imprecision.



Latest paper from Kevin Hall's group at the NIH.

The bottom two charts in this pic tell the story:

1597187245944.png

Same subject eating the same meals on the same occasion. On the left, quinoa/walnut/berry cereal (Meal A) versus bagel (Meal B) as measured by Abbott Libre Pro; versus Dexcom on the right.
 

trophywench

Well-Known Member
Relationship to Diabetes
Type 1
I may be thick - though I didn't think so all in all - but for what possible reason is this info of interest to yer average diabetic? I always thought that each person using a CGM needed to calibrate his CGM by means of BG testing alongside CGM results, to get the CGM algorithm attuned to his own metabolism so that it began to report reliable results for him.

Plus if the person started off with a reading of 0 mg/Dl in each case, wasn't he dead before eating the meals?

Plus what did he do yesterday and was there an R in the month?

So many imponderables possible Eddy.
 

Bruce Stephens

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Relationship to Diabetes
Type 1
I may be thick - though I didn't think so all in all - but for what possible reason is this info of interest to yer average diabetic? I always thought that each person using a CGM needed to calibrate his CGM by means of BG testing alongside CGM results, to get the CGM algorithm attuned to his own metabolism so that it began to report reliable results for him.

Plus if the person started off with a reading of 0 mg/Dl in each case, wasn't he dead before eating the meals?
The graphs are showing incremental glucose responses and the experiments were with people wearing both CGMs concurrently (so they're showing some difference between the CGMs, not differences between people).

(So the 0 really just means that's the beginning of the graph.)
 

mikeyB

Well-Known Member
Relationship to Diabetes
Type 1
The Libre doesn’t require calibration. My later comments were similar to Bruce’s - he’s a quicker typist:)
 

Bruce Stephens

Well-Known Member
Relationship to Diabetes
Type 1
The Libre doesn’t require calibration.
The Dexcom G4 Platinum is the other one (other than the Libre Pro) and they say that was calibrated as recommended.

(I must admit I wouldn't have thought calibration would matter either way for this, but they've followed manufacturer recommendations.)
 

Docb

Moderator
Relationship to Diabetes
Type 2
I'm still trying to work out what the first sentence of the conclusion means.
 

Pumper_Sue

Well-Known Member
Relationship to Diabetes
Type 1
The Dexcom G4 Platinum is the other one (other than the Libre Pro) and they say that was calibrated as recommended.
The G4 hasn't been in production for ages. We have had the G5 and G6 since then.
 

Pumper_Sue

Well-Known Member
Relationship to Diabetes
Type 1
The study (28 days, I think) started 1 March 2018 (according to the trial registration).
In that case G4 was almost at the end of it's days. I only used the G4 because it linked to my pump. But I believe the G5 was out then or ready to be launched so basically trial meaningless and a waste of money.
 

Bruce Stephens

Well-Known Member
Relationship to Diabetes
Type 1
I only used the G4 because it linked to my pump. But I believe the G5 was out then or ready to be launched so basically trial meaningless and a waste of money.
Well, only if we think these differences were due to some problems with the G4 Platinum which are fixed in the G5 (and have stayed fixed in the G6).

That may be the case, but for all I know it may be the case that the same test performed with two sensors of the same kind might show the same sorts of difference. (Actually maybe we have some reason to doubt that; I seem to remember trials being performed with people wearing two Libre sensors at the same time so significant differences would presumably have shown up in those.)
 
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