According to a press release from the FDA, "The four observational studies evaluated large patient databases and all reported some level of association between the use of insulin glargine, and other insulin products, and various types of cancer. The duration of patient follow-up in all four studies was shorter than what is generally considered necessary to evaluate for cancer risk from drug exposure."
There were also some inconsistencies in the studies which may indicate that a link between Lantus and cancer risk is weak to nonexistent.
The FDA is in the process of looking at these studies as well as other clinical trials to try to get a better picture of whether the increased risk of cancer does exist. The manufacturer of Lantus is working with the FDA to determine whether additional studies are required to establish the safety of Lantus.
As of right now, the FDA is recommending that people do not stop taking Lantus if it has been prescribed for them. Uncontrolled blood sugar levels can cause serious complications both short and long term. Contact your doctor if you have any concerns about Lantus.