What was the research looking at?
Four articles published in 'Diabetologia – The Journal of the European Association for the Study of Diabetes' – looked at the risk of cancer largely in people with Type 2 diabetes treated with insulin, particularly glargine insulin (Lantus).
The studies in the articles were based in Germany, Sweden, Scotland and the UK. In total, the data of 301,136 people treated with insulin was reviewed for the studies, of which 34,392 were taking glargine insulin (Lantus) alone.
What were the findings?
The first study, from Germany, suggested that there might be a small increase in the risk of cancer in those taking glargine as their only insulin. The strongest link seemed to be with breast cancer in older people.
This small increase in risk appeared in two of the other three studies as well, and seemed to be more so in people on high doses. It should be stated firmly that the evidence was not conclusive.
Following review of all available information the European Agency’s Committee for Medicinal Products for Human Use (CHMP) concluded that the available data is not a cause for concern.
Why is the evidence not conclusive?
The Committee carried out an in-depth review of the studies and the results. Owing to the type of methods used the studies were found to be inconclusive.
There limitations with the research undertaken were that the studies were observational and not clinical trials. It is important to recognise this difference. Observational studies can not tell cause and effect.
Clinical trials, however, ensure that people studied have all the same characteristics such as age, body mass index (BMI), blood pressure and the only difference is the treatment they are on. This means researchers can compare effects of treatment alone.
People in observational studies such as these may have many differing characteristics. These biases and differing characteristics are usually accounted for but in this case there is some doubt in the way that some of the trials corrected for these biases.
This means that researchers cannot be sure that the link is due to the insulin and not the differing characteristics. The link found between glargine insulin and breast cancer was not conclusive as the numbers in the studies were too small.
What does this mean for people with diabetes?
The review has recommended that a change in the way that glargine is prescribed is not necessary.
What does Diabetes UK advise to people using glargine insulin?
Diabetes UK would strongly advise people who are using glargine insulin to continue to take their medication as prescribed. You will become very ill if you stop taking your insulin.
If you are concerned about these findings then you should speak to your healthcare team about your anxieties before discontinuing any treatment. There are alternative insulins that can be used.
Diabetes UK has looks at guidance and takes a lead from the Medicines and Healthcare Products Regulatory Agency (MHRA) and to the National Institute of Health and Clinical Excellence (NICE) about insulin and how it should be prescribed to people with diabetes to ensure the best possible outcome for them.
The European Medicines Agency (EMEA) has stated that the relationship between glargine insulin and cancer cannot be confirmed or excluded and suggests that further studies are needed. They advise that people using glargine insulin should continue their usual treatment.
What if I have a strong family history of breast cancer?
If you are a woman with diabetes who has a strong family history of breast cancer, you do have the option of changing your insulin as does everyone – see your doctor if you would like more information.
What if I have cancer and I am using glargine?
Insulin itself is a very safe form of treatment and is vital for people with diabetes. No medication would be permitted to be prescribed unless proven safe by the regulatory bodies in the UK. There is a rigorous process in place for this. Do not stop taking your insulin without discussing it with your healthcare team first.
Reviewed July 2009.