peer reviewed ; Sitagliptin (Januvia), the first selective inhibitor of dipeptidylpeptidase-4, has been assessed in a large Belgian prospective observational study. The aim of the SUGAR study was to evaluate the efficacy of sitagliptin, at a dose of 100 mg once daily, when it was added in patients with uncontrolled type 2 diabetes followed in real life conditions. In the intent-to-treat population (n = 605), mean glycated haemoglobin level decreased from 8.41 +/- 1.18% to 7.29 +/- 0.86% after a follow up averaging 110 days (p < 0.0001). Similarly, mean fasting plasma glucose level decreased from 180 +/- 50 mg/dl to 141 +/- 37 mg/ dl (p < 0.0001). The improvement of these two parameters was observed independently of basal demographic characteristics, but was directly influenced by baseline initial corresponding values. The vast majority of patients included in SUGAR were initially treated by metformin as monotherapy (current criterion for sitagliptin reimbursement in Belgium); metformin daily dose slightly decreased when sitagliptin was added (from 1975 +/- 681 mg to 1919 +/- 667 mg; p = 0.033). Patients receiving other glucose-lowering agents, as single or combined therapies, had also a significant alleviation of their treatment when sitagliptin was added. After 3-6 months of follow up, more than 95% of patients still received sitagliptin, arguing for both the efficacy and the good tolerance of this new oral antidiabetic agent in clinical practice.