Sanofi's Lantus shows no cancer, heart risks: study PARIS (Reuters) - Sanofi's insulin Lantus does not put people at risk of cancer, heart attacks or strokes when taken over long periods, according to a major study in which the drug failed to prove it can prevent heart disease in early-stage diabetics. Although a positive result on heart disease could have widened Lantus's use, the findings of the longest and largest study of its kind should help shake off safety concerns about the French group's top-selling drug after a 2009 cancer scare. A number of studies at the time suggested a possible link between Lantus and a heightened risk of cancer, with conflicting results. "We know what the risks are of taking insulin on a long-term basis, and they are low," said the principal investigator of the trial, Hertzel Gerstein of McMaster University in Ontario, Canada, in a telephone interview with Reuters. The closely watched study also found that people with pre-diabetes who received daily Lantus injections had a 28 percent lower chance of developing diabetes, even after the injections stopped. The study tested more than 12,500 people at risk or in the early stages of diabetes with either a daily injection of Lantus or standard therapy for an average of six years. The results confirmed two known side effects of insulin - low blood sugar levels and modest weight gain. Researchers said these were minor reactions. The study also discovered that daily doses of Lovaza, a prescription pill based on fish oil and sold by Pronova Biopharma and GlaxoSmithKline, did not prevent heart-related deaths in diabetics. The findings were presented on Monday at the American Diabetes Association congress in Philadelphia, U.S., and published online in the New England Journal of Medicine. Paris-based Sanofi said it would extend the study by two years to gather further data on Lantus. Worldwide, Lantus has 80 percent of the market for long-acting, or basal, insulin used to treat diabetes, generating sales of around 3.9 billion euros ($4.9 billion) last year, representing 12 percent of Sanofi's total sales. Sanofi is particularly reliant on Lantus because it faces a wave of patent expirations on other blockbuster medicines. Fresh competition is emerging as rival drugmakers, such as U.S. group Eli Lilly and Danish company Novo Nordisk, prepare to launch newer long-acting insulin, in addition to the threat of biosimilars. The insulin market is also vulnerable to the growth of GLP-1 therapies, including Sanofi's own Lyxumia, which is in late stage development. Reporting by Elena Berton; Editing by Dan Lalor