Abstract Aims To assess the long-term glycaemic effects, concomitant changes in medications, and initiation of permanent insulin use (defined as daily insulin use for a period of ≥90 days, or ongoing use at death/final visit) with pioglitazone vs. placebo in diabetic patients receiving metformin or sulphonylurea monotherapy at baseline in the PROspective pioglitAzone Clinical Trial in macroVascular Events (PROactive). Methods In PROactive, patients with Type 2 diabetes and macrovascular disease were randomized to pioglitazone (force-titrated to 45 mg/day) or placebo, in addition to other existing glucose-lowering therapies. In a post-hoc analysis, we categorized patients not receiving insulin at baseline and treated by oral monotherapy into two main cohorts: addon to metformin alone (n = 514) and sulphonylurea alone (n = 1001). The follow-up averaged 34.5 months. Results There were significantly greater reductions in glycated haemoglobin (HbA1c) with pioglitazone than with placebo and more pioglitazone-treated patients achieved HbA1c targets, irrespective of the baseline oral glucose-lowering regimen and despite a decrease in the use of other glucose-lowering agents. Approximately twice as many in the placebo groups progressed to permanent insulin use than in the pioglitazone groups across the two cohorts: 3.4% for pioglitazone and 6.5% for placebo when added to metformin monotherapy and 6.3% and 14.8%, respectively, when added to sulphonylurea monotherapy. The overall safety of both dual therapies was good. Conclusions Intensifying an existing oral monotherapy regimen to a dual oral regimen by adding pioglitazone resulted in sustained improvements in glycaemic control and reduced progression to insulin therapy. The efficacy and safety of adding pioglitazone to either metformin monotherapy or sulphonylurea monotherapy were good.