OBJECTIVES: To evaluate the dosing of sitagliptin for type 2 diabetes mellitus (T2DM) patients with renal impairment. METHODS: This was a retrospective cross-sectional analysis using the General Electric Electronic Medical Records. The study population (N=1539) was patients with T2DM and renal impairment (defined using ICD-9-CM codes) who were prescribed sitagliptin between April 1, 2006 and June 30, 2008. Based on the label, 100mg of sitagliptin is the recommended dose for patients with normal or mild renal impairment (CrCl≥50), 50mg for patients with moderate renal impairment (50>CrCl≥30), and 25mg for severe or end-stage renal disease (ESRD)(30>CrCl).  Baseline severity of renal impairment was determined using calculated GFR values using the 4-point Modification of Dosing in Renal Disease (MDRD) formula. Patients with GFR level ≥60 were considered normal to mild cases, 30 to <60 were moderate cases, 15 to <30 were severe cases, and <15 or patients on dialysis had ESRD. Univariate analysis was done on age, gender, race, US region, payment source, comorbidities and Charlson-comorbidity index to identify factors that may be associated with inappropriate dosing. RESULTS: Of the 1,539 renally impaired patients with T2DM who received sitagliptin, 804(52%) had moderate renal impairment and 158(11%) had severe renal impairment or ESRD.  Two-thirds of all moderate to severe and ESRD renally impaired patients had initial sitagliptin prescriptions that were higher-than-recommended doses. At 12-month follow-up, 87% of patients, whose initial prescription was for a higher-than-recommended-dose of sitagliptin, continued to be on the inappropriate higher dose. Univariate analysis showed there were no significant differences in dosing by age, gender, race, US region, insurance type or comorbidities. CONCLUSIONS: Indiscriminant of patient characteristics, 2/3’s of the population of sitagliptin users recommended a lower dose due to renal impairment, were found to be inappropriately dosed higher-than-recommended. This inappropriate dosing was not corrected during a year-long follow-up.