A new study indicates that the diabetes drug pioglitazone, also known as Actos, could slash the risk of stroke and heart attack in patients — but the drug comes with some huge risks.

In a study funded by the National Institutes of Health, pioglitazone was shown to reduce stroke and heart attacks by about a quarter in those with insulin resistance but who do not have diabetes, according to an NIH release.

What you may not know is Actos is one of the best-selling drugs in the entire United States. In 2008, it was 10th overall, with sales of $2.4 billion.

In the past, studies on cardiovascular outcomes with pioglitazone were inconclusive, and the drug wasn’t showing any significant impact with regard to heart attacks and strokes although it was decreasing blood sugar levels.

The problem with pioglitazone is its side effects — and there are a number of serious ones.

In February 2007, Takeda Pharmaceutical Company, the developer of Actos, noted a greater incidence of fractures in the limbs of female diabetics.

In addition, those who take pioglitazone sometimes see an increase in fluid retention and therefore run the risk of edema, which can result in heart failure due to fluid overload.

Still another side effect involves mild weight gain. This happens due to an increase in subcutaneous adipose tissue.

There were a few other more minor side effects, including sinusitis, headache, and tooth problems.

Further controversy over the drug came in 2011 when the French Agency for the Safety of Health Products withdrew pioglitazone over concerns about a high risk of bladder cancer based on a study. U.S. regulators later added a warning to the drug’s label about this risk.