This is the first time that a diabetes drug has been shown to lower the rate of risk of cardiovascular disease and goes against previous research that suggested that glitazones could increase the risk of heart failure.
Atherosclerosis is estimated to be the cause of death in 75 per cent of patients with diabetes.
The findings of the PERISCOPE trial, presented this week at the American Cardiology Conference (ACC) in Chicago, showed that in a head-to-head trial pioglitazone was more effective at lowering the rate of progression of plaque build-up than the sulfonylurea glimepiride.
The researchers compared the effects of the two drugs on the rate of progression of coronary atherosclerosis in 543 patients with type-2 diabetes and coronary disease.
Patients received either pioglitazone (15-45mg) or glimepiride (1-4mg) for 18 months.
Atherosclerosis progression was measured by the change in percent atheroma volume (PAV), a marker for plaque build-up.
At the end of the study, those that had taken pioglitazone showed a 0.16 per cent decrease in PAV compared with a 0.73 per cent increase in the patients on glimepiride.