The five-year study, called the “Insulin Resistance Intervention after Stroke” trial or “IRIS” trial, investigated the effect of pioglitazone on strokes and heart disease. The results? Compared to a placebo, pioglitazone led to a striking 24% reduction in fatal and non-fatal heart attacks and strokes. Moreover, the rate of new diabetes cases was reduced by 52% in those using pioglitazone compared to placebo.