Age and Red Blood Cell Parameters Mainly Explain the Differences Between HbA1c and Glycemic Management Indicator
Pablo Azcoitia1, Raquel Rodríguez-Castellano1, Pedro Saavedra2
1Section of Endocrinology and Nutrition, Complejo Hospitalario Universitario Insular-Materno Infantil, Las Palmas de Gran Canaria, Spain.
Journal of Diabetes Science and Technology
|August 12, 2023
Summary
Glycated hemoglobin (HbA1c) and glucose management indicator (GMI) often differ in patients with diabetes. Easily measured factors like age, mean corpuscular volume (MCV), and red cell distribution width (RDW) can help explain these glycemic control discrepancies.
Area of Science:
- Endocrinology
- Diabetes Management
- Clinical Chemistry
Background:
- Glycated hemoglobin (HbA1c) is the standard for assessing diabetes glycemic control.
- Glucose management indicator (GMI) from continuous glucose monitoring (CGM) is a proposed alternative.
- Discrepancies between HbA1c and GMI can complicate clinical decisions.
Purpose of the Study:
- To identify factors contributing to the difference between HbA1c and GMI.
- To improve the interpretation of glycemic control metrics in diabetic patients.
Main Methods:
- Retrieved HbA1c measurements and corresponding 14-day CGM data (Freestyle Libre 2) from 339 type 1 diabetes patients.
- Selected data with at least 70% CGM sensor usage.
- Collected clinical, glucometric, and laboratory data concurrent with HbA1c measurements.
Main Results:
- A significant difference between HbA1c and GMI (absolute difference <0.3%) occurred in only 38.7% of 646 paired measurements.
- Univariate analysis linked HbA1c-GMI differences to age, diabetes duration, eGFR, MCV, RDW, and time in range (180-250 mg/dL).
- Multilevel modeling identified age and RDW (positive correlation) and MCV (negative correlation) as significant predictors of HbA1c-GMI difference.
Conclusions:
- Clinically relevant differences between HbA1c and GMI are common.
- Age and hematological parameters (MCV, RDW) aid in interpreting HbA1c-GMI discrepancies.
- These factors can enhance the clinical utility of CGM-derived metrics.
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