The European Medicines Agency is to investigate a possible link between insulin glargine (Lantus) use and cancer risk, after studies highlighted safety concerns.
The first study to suggest a link was a German study of 127,031 insulin-treated patients who used insulin glargine.
The researchers found that out of every 100 people who used insulin glargine over an average of about one and a half years, one additional patient was diagnosed with cancer.
The study also showed the risk of cancer appeared to be dose-dependent. Patients on a 50U dose of insulin glargine were 31 per cent more likely to develop cancer, but those taking a 10U dose had a 9 per cent raised risk.
The findings of this study were followed up in research carried out in Sweden and Scotland. The Swedish study found an increased risk of breast cancer among patients taking insulin glargine, but the Scottish study found only a non-significant increased risk for breast cancer.
Additionally, a UK study failed to find any link between insulin glargine and cancer.
The European Association for the Study of Diabetes concluded that patients should not stop taking insulin glargine on the basis of the findings of the studies.
Edwin Gale, professor of diabetes at Bristol University, led the UK study, and edits Diabetologia, the journal that published all four studies. He said: 'Our studies establish that there is a clear case for urgent investigation of a possible link between glargine and cancer.
'This can be done in a short time with access to larger registries and data meta-analysis.'
The formal advice, therefore, to patients taking glargine is to keep going for the time being until these issues are put to rest, said Professor Gale.
'This particularly applies to people with type-1 diabetes, who showed no excess cancer risk in our studies, and those who have derived clear benefit from its use.'
Jean-Pierre Lehner, chief medical officer for sanofi-aventis, which markets Lantus, said: 'We consider that the results of these patient registries are not conclusive.'
Comment below and tell us what you think