Aims/Introduction. To describe patterns of long-term glycemic control among patients with type 2 diabetes in Isfahan, Iran and identify factors associated with glycemic control. Methods. During the mean (standard deviation (SD)) follow-up period of 8.4 (4.2) (range 1-18) years, 4,582 patients with type 2 diabetes have been examined to determine glycemic changes. Their glycated hemoglobin (GHb) at the last clinic visit was compared with the initial visit data. The mean (SD) age of participants was 49.3 (9.6) years with a mean (SD) duration of diabetes of 5.0 (5.1) years at initial registration. Results. Mean (SD) GHb was 8.7% (2.3) at baseline and 7.9% (1.9) at the study end and decreased by mean of 0.8% (95% confidence interval (CI) 0.74, 0.87; P < 0.001) and varied by the severity of baseline GHb. 74.6% at the initial visit versus 64.4% at the last clinic visit had GHb values above the target level of 7.0%. Using a stepwise multiple regression models, age, higher GHb, FPG, follow-up period, and number of follow-up visits increased and higher systolic BP and female gender significantly decreased the percent glycemic change. Conclusions. This study highlights that more than 64.4% of the patients have GHb values higher than 7.0% at last clinic visit andindicatesthe difficult challenges physicians face when treating their patients with type 2 diabetes. Clinical efforts should focus on more effective methods for glycemic control in diabetic patients.