Objective: The aim of this study is to investigate the length of telomere and serum silent information regulator-1 levels in type 2 diabetic subjects as well as their associations with body composition, glycemic control, and diabetic complications. Methods: We enrolled 84 type 2 diabetic subjects and 40 controls. The length of telomere and serum silent information regulator-1 (Sirtuin-1) levels, body composition and diabetic complications were examined. Results: Median T/S ratio tended to be lower in type 2 diabetic subjects compared to the controls (1.03 (0.20-1.48) vs. 1.25 (0.80-1.69), P=.064); however, the percentage of having shorter telomere (T/S ratio < 1) was significantly higher in type 2 diabetic subjects than in the controls (47.6% vs. 27.5%, P=.035). Serum Sirtuin-1 level was lower in type 2 diabetic subjects than in controls (95.48 ± 29.9 vs. 138.40 ± 42.66 pg/mL, P < .001). There were no differences in the length of telomere and serum sirtuin-1 between the groups divided according to the presence of diabetic complications (P > .05). The percentage of having shorter telomere was higher in obese patients than in non-obese patients with DM (35.7% vs. 60%, P=.029). The T/S ratio was correlated with truncal fat in type 2 diabetic subjects (r=−0.250, P=.028). Conclusions: The length of telomere and silent information regulator-1 may have a role in cellular aging in type 2 diabetic subjects in relation to visceral obesity.