July 25, 2012 -- If you have diabetes or prediabetes, fish oil supplements might not be so helpful after all in cutting heart disease risk.

That's the conclusion of a large study published in The New England Journal of Medicine.

Fish oil supplements contain omega-3 fatty acids. The American Heart Association says omega-3s have been shown to benefit the hearts of people at high risk for heart disease.

But in the new study, people with type 2 diabetes or prediabetes who took omega-3 fatty acid supplements were no less likely to die or suffer a heart attack or stroke than patients who did not take the supplements.

Last April, a review of studies involving more than 20,000 patients with heart disease found the same thing.