Abstract: FR-PO0353
Discordance Between Glucose Management Indicator and Hemoglobin A1c in CKD
Session Information
- Diabetic Kidney Disease: Progression, Predictive Tools, Therapeutics, and Outcomes
November 07, 2025 | Location: Exhibit Hall, Convention Center
Abstract Time: 10:00 AM - 12:00 PM
Category: Diabetic Kidney Disease
- 702 Diabetic Kidney Disease: Clinical
Authors
- Tang, Mengyao, Mass General Brigham Inc, Boston, Massachusetts, United States
- Percy, Shananssa, Mass General Brigham Inc, Boston, Massachusetts, United States
- Kalim, Sahir, Mass General Brigham Inc, Boston, Massachusetts, United States
Background
A1C has major limitations in CKD, including bias introduced by urea-driven carbamylation, altered erythrocyte lifespan, and inability to capture glycemic variability. Continuous glucose monitoring (CGM)–derived Glucose Management Indicator (GMI) converts mean glucose into A1C units and better reflects glycemia when A1C is unreliable. We aimed to identify clinical predictors of discordance between GMI and A1C in CKD.
Methods
In this prospective study of adults with type 2 diabetes on stable regimens and CKD stages 3–5 not yet on dialysis, participants wore 10-day blinded Dexcom G6 CGM and had A1C measured. We calculated each participant’s GMI – A1C difference, visualized agreement and bias with a Bland-Altman plot, and categorized them as positive discordant (GMI – A1C ≥ 0.5%), negative discordant (GMI – A1C ≤ –0.5%), or concordant (|GMI – A1C| < 0.5%, reference). Logistic regression evaluated associations of discordance with demographics, lab values, diabetes medications and CGM metrics.
Results
Among 37 participants, 73% were male; mean age 74 years; mean eGFR 38 mL/min/1.73 m2. Diabetes regimens included insulin (43%), metformin (32%), SGLT2i (32%), incretin-based therapies (38%), DPP-4i (8%), and sulfonylureas (22%). Discordance occurred in 40% of participants (Fig 1): positive discordance in 24% and negative discordance in 16%. Elevated urea was significantly associated with positive discordance (P = 0.04), while higher glucose coefficient of variation was associated with negative discordance (P = 0.02). No significant associations were observed for age, sex, race, hemoglobin, eGFR, or medications.
Conclusion
Among CKD patients, discordance between GMI and A1C is common. Elevated urea level, a surrogate for carbamylation, is a predictor of higher GMI relative to A1C, suggesting that A1C underestimates glycemia in patients with high carbamylation burden. In contrast, increased coefficient of variation is a predictor of lower GMI relative to A1C, suggesting that A1C overestimates glycemia in patients with high glycemic variability.
Funding
- Commercial Support – Dexcom (device donation only, no direct funding)