Background In recent years, increasing evidence suggests a potential importance of telomere biology in type 2 diabetes. The aim of this study was to determine whether sitagliptin, a medicine generally used in diabetes, can influence the telomere and telomerase in newly diagnosed type 2 diabetic patients. Methods Type 2 diabetic patients (T2D, n=38) and non-diabetic subjects (control, n=31) were randomly selected from the outpatient of Tongji Hospital, Tongji Medical College, Huazhong university of Science and Technology. Leukocyte telomere length ratio was measured using a quantitative polymerase chain reaction and was analysed. Telomerase activity was measured by polymerase chain reaction enzyme-linked immunosorbent assay method. Peripheral insulin resistance (homeostasis model assessment) was calculated from fasting plasma glucose and fasting plasma insulin. Results Telomere length of the type 2 diabetic patients (1.58+/-0.57) was significantly shorter than those of control subjects (3.98+/-0.90) and was significantly elongated after intervention by sitagliptin. There was no significant difference between the T2D and control group in telomerase activity, and the treatment of sitagliptin in T2D group showed no significant effect on the telomerase activity. Conclusions In type 2 diabetes patients, leukocyte telomere length is significantly reduced, whereas the telomerase activity seems less influenced. Sitagliptin might protect beta-cells in the pancreas by elongating the telomere length. Copyright (C) 2014 John Wiley & Sons, Ltd.