DPP4 and diabetes mellitus: In an established animal model of diabetes, obtained with administration of a low-dose streptozotocin (STZ) and high-fat diet (HFD), the HFD/STZ rat exhibiting both hyperglycemia and hyperinsulinemia, oral daily administration of linagliptin (1, 3, 10 mg/kg), for 4 weeks, produces a dose-dependent inhibition of plasma DPP-4 (by 59, 78, and 87% with increasing doses) vs. levels at time 0, when measurements are carried out at the end of the study period (day 27), 21 h after last administration of the drug (Thomas et al., 2009).