Discordance between HbA1c and average blood sugar in CKD Patients with Diabetes, reveals study
Glycated haemoglobin A1c (HbA1c) and self-monitoring of blood glucose (SMBG) are cornerstones of glycemic monitoring in patients with diabetes. This means that the time available for the glycation of haemoglobin is identical. Several studies have found a reduced erythrocyte lifespan in patients on hemodialysis and proposed this as a key mechanism for lowering HbA1c because the glycation of haemoglobin is a continuous process throughout the erythrocyte lifespan.
A recent study suggests that there is discordance between HbA1C and glucose management indicator (GMI) derived from continuous glucose monitoring (CGM) data in patients with CKD. Therefore continuous glucose monitoring (CGM) provides a more precise glucose measure than HbA1c in patients with diabetes and chronic kidney disease (CKD). The study findings were published in the Journal of Diabetes Science and Technology on April 25, 2022.
The latest guidelines from Kidney Disease Improving Global Outcomes emphasize the uncertainty of HbA1c. The glucose management indicator (GMI) derived from continuous glucose monitoring (CGM) data could be an alternative. However, the concordance between HbA1c measured in the laboratory and GMI (HbA1c-GMI) is uncertain in individuals with CKD. Therefore, Dr Philippe Oriota and his team conducted a study to analyze this discrepancy.
In this multicentric, retrospective, observational study, the researchers included patients with diabetes and CKD (n = 170) and compared them with a group of individuals with diabetes without CKD (n = 185). They used intermittently scanned continuous glucose monitoring (isCGM) for glucose monitoring. They compared the 14-day and 90-day glucose data recorded by the isCGM to calculate GMI and the discordance between lab HbA1c and GMI. They further analyzed the obtained data by a Bland-Altman method and linear regression.
Key findings of the study:
- Upon analysis, the researchers found that HbA1c-GMI discordance was significantly higher in the CKD group versus without the CKD group (0.78 ± 0.57 [0.66-0.90] vs 0.59 ± 0.44 [0.50-0.66]%.
- They found an absolute difference >0.5% in 68.2% of individuals with CKD versus 42.2% of individuals without CKD.
- They further suggested a new specific formula to estimate HbA1c from the linear regression between HbA1c and mean glucose CGM, namely CKD-GMI = 0.0261 × 90-day mean glucose (mg/L) + 3.5579 (r2 = 0.59).
The authors concluded, "HbA1c-GMI discordance is frequent and usually in favor of an HbA1c level higher than the GMI value, which can lead to errors in changes in glucose-lowering therapy, especially for individuals with CKD. This latter population should benefit from the CGM to measure their glucose exposure more precisely."
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