OBJECTIVE To examine the efficacy and safety of rimonabant, a selective cannabinoid receptor type-1 antagonist, in patients with type 2 diabetes receiving insulin monotherapy. RESEARCH DESIGN AND METHODS Patients (n = 368; A1C > or =7%) were randomized to 20 mg/day rimonabant or placebo in this 48-week, double-blind, placebo-controlled multicenter trial. Change in baseline A1C to week 48 (primary outcome) and changes in body weight, waist circumference, and lipid levels (secondary outcomes) were assessed. RESULTS Rimonabant significantly reduced baseline A1C versus placebo (-0.89 vs. -0.24%; P < 0.0001), and significantly greater improvements were observed in cardiometabolic risk factors. More rimonabant patients achieved >10% reduction in mean total daily insulin dose versus placebo (P = 0.0012), and fewer required rescue medication (P < 0.0001). Hypoglycemia, nausea, dizziness, anxiety, and depression were more frequent with rimonabant. CONCLUSIONS Rimonabant improved glycemic control and cardiometabolic risk factors in patients with type 2 diabetes receiving insulin.