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The relative contribution of diurnal and nocturnal glucose exposures to HbA1c in type 1 diabetes males: a pooled analysis

Lookup NU author(s): Dr Daniel WestORCiD



This work is licensed under a Creative Commons Attribution 4.0 International License (CC BY 4.0).


© 2022, The Author(s). Purpose: The exact contribution of daily glucose exposure to HbA1c in people with type 1 diabetes (T1D) remains controversial. We examined the contribution of pre- and postprandial glycaemia, nocturnal and early-morning glycaemia, and glycaemic variability to HbA1c levels in T1D. In this analysis, we used clinical data, namely age, BMI and HbA1c, as well as glycaemic metrics (24-h glycaemia, postprandial, nocturnal, early-morning glycaemia, wake-up glucose, and glycaemic variability) obtained over a four-week period of continuous glucose monitoring (CGM) wear in thirty-two males with T1D. Methods: The trapezoid method was used estimate the incremental area under the glucose curve (iAUC) for 24-h, postprandial (3-h period following breakfast, lunch, and dinner, respectively), nocturnal (between 24:00–04:00 AM), and early-morning (2-h period 2-h prior to wake-up) glycaemia. Linear regression analysis was employed whereby CGM-derived glycaemic metrics were explanatory variables and HbA1c was the outcome. Results: Thirty-two T1D males (mean ± SD: age 29 ± 4 years; HbA1c 7.3 ± 0.9% [56 ± 13 mmol/mol]; BMI 25.80 ± 5.01 kg/m2) were included in this analysis. In linear models adjusted for age and BMI, HbA1c was associated with 24-h mean glucose (r2 = 0.735, p < 0.001), SD (r2 = 0.643, p = 0.039), and dinner iAUC (r2 = 0.711, p = 0.001). CGM-derived metrics and non-glycaemic factors explained 77% of the variance in HbA1c, in which postprandial glucose accounted for 32% of the variance explained. The single greatest contributor to HbA1c was dinner iAUC resulting in 0.6%-point (~7 mmol/mol) increase in HbA1c per SD increase in dinner iAUC. Conclusions: Using comprehensive CGM profiling, we show that postprandial glucose, specifically evening-time postprandial glucose, is the single largest contributing factor to HbA1c in T1D. Trial registration number: NCT02204839 (July 30th 2014); NCT02595658 (November 3rd 2015).

Publication metadata

Author(s): Campbell MD, West DJ, O'Mahoney LL, Pearson S, Kietsiriroje N, Holmes M, Ajjan RA

Publication type: Article

Publication status: Published

Journal: Journal of Diabetes and Metabolic Disorders

Year: 2022

Volume: 21

Pages: 573-581

Print publication date: 01/06/2022

Online publication date: 31/03/2022

Acceptance date: 28/02/2022

Date deposited: 19/04/2022

ISSN (electronic): 2251-6581

Publisher: Springer Netherlands


DOI: 10.1007/s40200-022-01015-1


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