Our primary analyses using multivariate Cox regression models identified a significantly higher risk of the primary endpoint of DKD progression with increasing HbA1c variability: compared with those in the lowest HbA1c variability quartile, participants in the highest quartile had HRs (95% CIs) of 7.76 (4.54, 13.26), 2.62 (1.75, 3.94) and 5.46 (3.40, 8.79) using methods 1–3, respectively, independent of risk factors such as age, HbA1c, log10-transformed ACR and SBP. This evidence concerns the gene ACR and diabetic kidney disease.