Imprecision nutrition? Duplicate meals result in unreliable individual glycemic responses measured by continuous glucose monitors across four dietary patterns in adults without diabetes

Abstract

Background: Continuous glucose monitors (CGMs) are being used to characterize postprandial glycemic responses and thereby provide personalized dietary advice to minimize glycemic excursions. However, the efficacy of such advice depends on reliable CGM responses. Objective: To explore within-subject variability of CGM responses to duplicate meals in an inpatient setting. Methods: CGM data were collected in two controlled feeding studies (NCT03407053andNCT03878108) in 15 participants without diabetes capturing 948 meal responses in duplicate ~1 week apart from three dietary patterns. One study used two different CGMs (Abbott Freestyle Libre Pro and Dexcom G4 Platinum) whereas the other study used only Dexcom. We calculated the incremental area under the curve (iAUC) for each 2-h post-meal period and compared within-subject iAUCs using the same CGM for the duplicate meals using linear correlations, intra-class correlation coefficients (ICC), Bland-Altman analyses, and compared individual variability of glycemic responses to duplicate meals versus different meals using standard deviations (SDs). Results: There were weak to moderate positive linear correlations between within-subject iAUCs for duplicate meals (Abbott r=0.47, p<0.0001, Dexcom r=0.40, p<0.0001), with low within-participant reliability indicated by ICC (Abbott 0.31, Dexcom 0.16). Bland-Altman analyses indicated wide limits of agreement (Abbott -31.4 to 31.5 mg/dL, Dexcom -32.3 to 31.6 mg/dL) but no significant bias of mean iAUCs for duplicate meals (Abbott 0.1 mg/dL, Dexcom -0.3 mg/dL). Individual variability of glycemic responses to duplicate meals was similar to that of different meals evaluated each diet week for both Abbott (SD_duplicate = 10.7 mg/dL , SD_week 1 =12.4 mg/dL, SD_week 2 =11.6 mg/dL, p=0.38) and Dexcom (SD_duplicate = 11.8 mg/dL, SD_week 1 =12.2 mg/dL, SD_week 2 =12.4 mg/dL, p=0.80). Conclusions: Individual postprandial CGM responses to duplicate meals were unreliable in adults without diabetes. Personalized diet advice based on CGM measurements in adults without diabetes requires more reliable methods involving aggregated repeated measurements.

Innovative Solution or Cause for Concern? The Use of Continuous Glucose Monitors in People Not Living with Diabetes: A Narrative Review.

“…The key assumption of PN studies is that an individual's unique response to the same meal is reproducible 54 has now been challenged. 56 With recent data showing poor reliability of PPGR to multiple duplicate meals, with intra-individual glucose variability similar to that seen across various meals. 56 Even under controlled experimental conditions, obtaining two measurements was insufficient to accurately estimate PPGR, however determining the number of CGM readings needed for accurate estimates remains ambiguous.…”

“…56 With recent data showing poor reliability of PPGR to multiple duplicate meals, with intra-individual glucose variability similar to that seen across various meals. 56 Even under controlled experimental conditions, obtaining two measurements was insufficient to accurately estimate PPGR, however determining the number of CGM readings needed for accurate estimates remains ambiguous. 56 Furthermore, the efficacy of CGM-driven meal assessments within PN may be device-dependent, given observed variances in inter-personal PPGR with different devices, 57 prompting reflections on genuine personalisation and use in T2DM prevention.…”

“…56 Even under controlled experimental conditions, obtaining two measurements was insufficient to accurately estimate PPGR, however determining the number of CGM readings needed for accurate estimates remains ambiguous. 56 Furthermore, the efficacy of CGM-driven meal assessments within PN may be device-dependent, given observed variances in inter-personal PPGR with different devices, 57 prompting reflections on genuine personalisation and use in T2DM prevention. The disparencies could, however, have arisen due to potential methodological challenges.…”

Innovative Solution or Cause for Concern? The Use of Continuous Glucose Monitors in People Not Living with Diabetes: A Narrative Review.

“…Recent debates have challenged the idea of predominantly inter-individual variability in PPGR, as opposed to intra-individual variability in PN [58]. Poor reliability of PPGR to multiple duplicate meals were reported, with intraindividual variability similar to variability across various meals [58].…”

“…Recent debates have challenged the idea of predominantly inter-individual variability in PPGR, as opposed to intra-individual variability in PN [58]. Poor reliability of PPGR to multiple duplicate meals were reported, with intraindividual variability similar to variability across various meals [58]. Even under controlled conditions, obtaining only two measurements was insufficient to accurately estimate PPGR, though determining the number of CGM readings for estimates remains ambiguous [58].…”