Imprecision nutrition? Different simultaneous continuous glucose monitors provide discordant meal rankings for incremental postprandial glucose in subjects without diabetes

Abstract

Background: High postprandial glucose excursions may increase risk for disease. Individuals have widely varying glucose responses to different meals, and precision nutrition approaches often seek to personalize diets to minimize postprandial glycemic responses as measured by continuous glucose monitors (CGMs). However, it is unknown whether different CGM devices result in concordant meal rankings according to postprandial glycemic excursions.

Objective: We explored whether meal rankings according to postprandial glycemic excursions differ between 2 simultaneously worn CGMs.

Methods: We collected 27,489 simultaneous measurements from Dexcom G4 Platinum and Abbott Freestyle Libre Pro CGMs during 28 inpatient days in 16 adults without diabetes. Simultaneous glucose measurements obtained for 2 h following 760 ad libitum meals were used to compare within-subject meal rankings between the CGM devices according to their incremental glucose response.

Results: Postprandial responses to ad libitum meals were highly variable, with the Abbott and Dexcom systems resulting in within-subject incremental mean ± SD glucose CVs of 91.7 ± 1.9% and 94.2 ± 2.7%, respectively. Within-subject meal rankings for incremental glycemic responses were relatively discordant between CGMs, with a mean Kendall rank correlation coefficient of 0.43 ± 0.05. Meals in the bottom compared with those in the top half of incremental glycemic responses ranked by Abbott resulted in 50 ± 10% (P = 0.0002) less glycemic reduction as measured by Dexcom, and vice versa. The missing glycemic reduction by eating meals ranked according to the discordant CGM was inversely correlated with each subject's Kendall rank correlation coefficient (r = -0.95; P < 0.0001).

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. This trial was registered at clinicaltrials.gov as NCT03407053.

Keywords: continuous glucose monitor; glucose variability; glycemia; personalized nutrition; precision nutrition.

Published by Oxford University Press on behalf of the American Society for Nutrition 2020.

Figures

Figure 1

Abbott continuous glucose measurements (A) in an example subject consuming 64 ad libitum meals illustrating incremental glucose responses with a CV of 77.3%. Dexcom continuous glucose measurements (B) simultaneously obtained in the same subject showing incremental glucose responses with a CV of 68.8%. Example of incremental glucose responses to meals A and B as measured by the Abbott system (C). (Meal A was a berry and walnut quinoa cereal and meal B was a plain bagel with cream cheese and turkey bacon.) The Dexcom system (D) measured comparatively discordant incremental glycemic responses to the same 2 meals simultaneously measured in the same subject.

Figure 2

Mean Abbott glucose responses (A) to the high- compared with the low-ranked half of 760 ad libitum meals according to the Abbott system. Mean Abbott glucose responses (B) in the same 16 subjects to the same high-ranked compared with the low-ranked meals according to the Dexcom system. Mean Dexcom glucose responses (C) to the meals ranked as high glycemic compared with those ranked as low glycemic by the Abbott system. Mean Dexcom glucose responses (D) to the meals ranked as high glycemic compared with those ranked as low glycemic by the Dexcom system. Difference between the Abbott- and Dexcom-measured glucose responses (E) for the meals ranked as high glycemic compared with those ranked as low glycemic by the Abbott system. Difference between the Abbott- and Dexcom-measured glucose responses (F) for the meals ranked as high glycemic compared with those ranked as low glycemic by the Dexcom system.