FAQ

Several recent European studies revealed a possible link between Lantus, a synthetic insulin used to treat diabetes, and cancer.

Lantus is an “analogue,” or artificial version, of insulin, injected once daily to treat Type 1 and Type 2 diabetes. The insulin is used to help control blood sugar over an extended period of time. It is manufactured by French drugmaker Sanofi-Aventis, and has been in use since 2000, when it received marketing authorization.

The European studies involve 301,136 insulin-treated patients in Germany, Sweden and Britain. The four observational studies evaluated large patient databases and all reported some level of association between the use of Lantus (insulin glargine), and other insulin products, and various types of cancer.

The link was strongest between Lantus use and breast cancer, although the absolute risk was small. Results of the largest study, conducted in Germany, indicated an incidence of about 1 extra cancer diagnosed for every 100 people taking Lantus compared with those on human insulin.

According to the report published in Diabetologia, the journal of the European Association for the Study of Diabetes (EASD), “Of particular note in this study was the finding that the increased risk of cancer was dose-dependent. Thus for patients given a dose of 10U, Lantus insulin alone increased the risk of cancer by 9% compared with human insulin; but for a dose of 50U, the increased risk was 31%.”

Reasoning regarding why Lantus may be linked to cancer has to do with the fact that Lantus is a synthetic rather than true human insulin. According to research, some anaglogues (artificial versions of insulin) have a structure that makes them more likely to bind to the body’s IGF-1 receptor (insulin-like growth factor), which mainly induces cell proliferation.

Despite the findings in this recent report, the FDA is urging patients not to stop using the medication. It calls for additional research because, “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.” The FDA says stopping or changing medications could also present immediate and long-term serious adverse events.

In a statement released following the Diabetologia report, the American Diabetes Association agreed with the FDA, urging patients to stick with their medication until further studies are completed. The ADA says, “For patients using glargine and considering switching to another form of insulin, the data in these studies make it unclear as to whether one type of insulin increases the risk of cancer more than other types of insulin.”

Patients are urged to talk to their doctor before making any decisions.