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Glucose-Derived Personalized HbA1c Correction (GDAC) Study to Improve Alignment Between CGM-Derived Metrics and HbA1c

Ramzi A Ajjan1, Pratik Choudhary2, Yongjin Xu3

  • 1The LIGHT Laboratories, Leeds Institute of Cardiovascular and Metabolic Medicine, University of Leeds, Leeds, U.K.

Diabetes Care
|June 8, 2026
PubMed

Insights

Glycated hemoglobin (HbA1c) and average glucose (AG) show discordance due to red blood cell (RBC) variations. A new personalized HbA1c (pA1C) metric significantly reduces this gap, improving diabetes management, especially for the Black population.

Area of Science:

  • Endocrinology and Metabolism
  • Clinical Chemistry
  • Diabetes Research

Background:

  • Glycated hemoglobin (HbA1c) and average glucose (AG) are key diabetes metrics.
  • Personal variations in red blood cell (RBC) physiology can cause discordance between HbA1c and AG.
  • This discordance complicates diabetes management and can exacerbate health disparities.

Purpose of the Study:

  • To quantify the extent of HbA1c-AG discordance in a diverse diabetic population.
  • To develop and validate a personalized HbA1c (pA1C) metric that accounts for individual RBC characteristics.
  • To assess the effectiveness of pA1C in reducing discordance and improving glycemic metric alignment.

Main Methods:

  • A 26-week prospective study involving individuals with type 1 and type 2 diabetes.
  • Collected HbA1c every 2 weeks and continuous glucose monitoring (CGM) data throughout.
  • Derived a personal glycation ratio (PGR) to calculate pA1C, analyzing its relationship with AG and comparing it to standard HbA1c.

Main Results:

  • 33% of 257 participants exhibited clinically significant (≥0.5%) HbA1c-AG discordance.
  • The Black population showed the highest discordance rate (41%).
  • pA1C reduced overall discordance to 14% (58% reduction) and in the Black population to 12% (71% reduction).

Conclusions:

  • HbA1c-AG discordance is a prevalent issue, disproportionately affecting the Black population.
  • The personalized HbA1c (pA1C) metric significantly improves the alignment between HbA1c and average glucose levels.
  • pA1C offers a promising approach to optimize diabetes management and mitigate health disparities.
Abstract

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