Glycated albumin (GA) is recognized as a reliable marker for short-term glycemic monitoring in diabetic patients. We investigated the clinical relevance of GA and the ratio of GA to glycated hemoglobin (A1c) in Korean type 2 diabetic patients. In this retrospective study, we compared A1c, GA, and the GA/A1c ratio and analyzed the relationship between glycemic indices and various parameters in 1,038 Korean type 2 diabetic patients. The patients were divided into two groups: a stably maintained A1c group whose A1c levels did not fluctuate by more than 0.5% for at least 6 months and an unstably maintained A1c group whose A1c levels fluctuated by more than 0.5%. Serum GA was strongly correlated with A1c in both groups. Fasting plasma glucose and postprandial glucose were correlated with GA in unstably maintained A1c group, whereas they were correlated with A1c in stably maintained A1c group. The GA/A1c ratio tended to increase as A1c increased. Postprandial glucose and body mass index affected the GA/A1c ratio. Our data show that serum GA may be a more useful glycation index than A1c for monitoring glycemic control in type 2 diabetic patients with fluctuating and poorly controlled glycemic excursions.