Background. Postkidney transplant diabetes mellitus (PTDM) affects cardiovascular, allograft, and recipient health. We tested whether early intervention with sitagliptin for hyperglycemia (blood glucose >200mg/dL) within the first week of transplant and discontinued at 3 mo could prevent development of PTDM in patients without preexisting diabetes. Methods. The primary efficacy objective was to improve 2-h oral glucose tolerance test (OGTT) by >20mg/dL at 3 mo posttransplant. The secondary efficacy objective was to prevent new onset PTDM, defined as a normal OGTT at 3 mo. Results. Sixty-one patients consented, and 50 patients were analyzed. The 3-mo 2-h OGTT (end of treatment) was 141.00±62.44mg/ dL in the sitagliptin arm and 165.22±72.03mg/dL (P=0.218) in the placebo arm. The 6-mo 2-h OGTT (end of follow-up) was 174.38±77.93mg/ dL in the sitagliptin arm and 171.86±83.69ng/dL (P=0.918) in the placebo arm. Mean intrapatient difference between 3- and 6-mo 2-h OGTT in the 3-mo period off study drug was 27.56+52.74mg/dL in the sitagliptin arm and −0.14+45.80mg/dL in the placebo arm (P=0.0692). At 3 mo, 61.54% of sitagliptin and 43.48% of placebo patients had a normal 2-h OGTT (P=0.2062), with the absolute risk reduction 18.06%. There were no differences in HbA1c at 3 or 6 mo between sitagliptin and placebo groups. Participants tolerated sitagliptin well. Conclusions. Although this study did not show a significant difference between groups, it can inform future studies in the use of sitagliptin in the very early posttransplant period.