Sodium glucose co-transporter 2 (SGLT-2) inhibitors are newly developed but promising medicine for type 2 diabetes. However, patients with a different renal threshold for glucose excretion (RTG) may have a different reaction to this medicine. Therefore, the objective of this study was to investigate the characteristics of RTG and its impact factors in patients with type 2 diabetes mellitus (T2DM). The clinical and laboratory data of 36 healthy individuals and 168 in-hospital patients with T2DM were collected and analyzed, RTG was calculated using blood glucose (BG) measured by dynamic BG monitoring, urinary glucose excretion (UGE) and estimated glomerular filtration rate (eGFR). The characteristics of RTG were investigated. The risk factors for high RTG were analyzed using non-conditional logistic regression analysis. Our results found that RTG of the T2DM group was higher than that of the healthy individuals (P < 0.05); and 22.22% from the healthy individuals group but 58.33% from the T2DM group had high RTG. Age, duration of diabetes, body mass index (BMI), and homeostasis model assessment insulin resistance index (HOMA-IR) were independently associated with high RTG (P < 0.05). Further stratified analysis revealed that RTG in T2DM patients increased with age, duration of diabetes, and BMI. In conclusion, RTG is increased in patients with T2DM, especially in those with longer diabetic duration, higher BMI, and those who are older. Therefore, these patients may be more sensitive to SGLT-2 inhibitors.