However, the authors did not present renal function or urine albumin excretion of the subjects, which can be important confounders in the study outcome. Not only advanced renal dysfunction, but also early change like microalbuminuria is well known as an independent factor of cardiovascular disease outcome [2]. In addition, it was recently reported that A1c variability was independently associated with the development of microalbuminuria in patients with type 2 diabetes [3]. Therefore, additional analysis including renal status might demonstrate a more clear relationship between A1c variability and coronary artery disease. Soon after the publication by Lee et al. [1], a contrary result was released that A1c variability had no major impact on macrovascular complications in patients with type 2 diabetes, which is in opposition to nephropathy [4].