HbA1c variability and diabetes complications: assessment and implications

Even though the long-term variability of glucose homeostasis has emerged as a risk factor for adverse out-comes in diabetes, there exists no universal consensus on its definition and assessment, but the determina-tion of quarterly HbA1c fluctuations would be an appropriate metric. From the analysis of retrospective studies conducted in persons with type 2 diabetes, the risk for adverse outcomes appears to become signifi-cantly increased when the coefficient of variation for HbA1c (%CV for HbA1c) is above 5.0%. However, should the number of HbA1c readings be greater than four for completing a clinically relevant assessment, the fol-low-up period would be longer than one year. Such a delay is not clinically acceptable for rapid clinical deci-sions. To conciliate the scientific relevance and practical approaches with minimal number of HbA1c measurements, we assessed the HbA1c variability from two successive HbA1c readings. For perspective in care the 5.0% threshold of the %CV for HbA1c was converted into lower and upper limits of visit-to-visit dif-ferences in absolute HbA1c levels. These HbA1c dependent limits (+/- 0.X% i.e., [X/10]% for an HbA1c level of X%) easily permit to decipher HbA1c stability and lability in diabetes across the spectrum of HbA1c levels and further to adjust the treatment.(c) 2022 Elsevier Masson SAS. All rights reserved.