Outcomes from intensive glycemic control postrenal transplant have not been studied. Our objective was to observe the optimal management of hyperglycemia in patients with diabetes or impaired glucose tolerance receiving renal transplantation. We conducted a randomized controlled trial with patients undergoing renal transplantation randomized to either i.v. insulin therapy (intensive) or standard s.c. insulin therapy while the patients were admitted to the hospital. The study consisted of a 3-day postrenal transplant group treated with intensive i.v. insulin [blood glucose (BG) = 70-110 mg/dl] or a control group treated with s.c. insulin (BG = 70-180 mg/dl). The primary endpoint was delayed graft function (DGF). Secondary endpoints were glycemic control, graft survival, and acute rejection episodes. A total of 104 patients were screened and randomized to either the intensive or control condition; however, the intention-to-treat analysis set consisted of only the 93 participants (n = 44 intensive, n = 49 control) that underwent a renal transplant. DGF was present in 18% (eight of 44) of the intensive group and 24% (12 of 49) of the control group (P = 0.46). The occurrence of severe hypoglycemia (BG < 40 mg/dl) and severe hyperglycemia (BG > 350 mg/dl) were the primary safety outcome measures. There were nine participants with hypoglycemia identified, seven of which (78%) were in the intensive treatment group (P = 0.08). There were 30 instances of hyperglycemia with five participants (11%) in the intensive group and 12 participants (24%) in the control group having at least one hyperglycemic event (P = 0.10). For the 11 rejection episodes, nine were in the intensive treatment group (P = 0.013). The primary outcome measure of DGF was not statistically different for the two treatment groups. Regarding longer-term rejection and graft survival, the intensively treated participants were at higher risk for a rejection episode.