http://www.pulsetoday.co.uk/story.as...de=4123806&c=1
Study raises new questions over insulin glargine cancer risk
02 Oct 09
By
Lilian Anekwe
A controversial trial by UK researchers has reopened the debate about a possible link between insulin glargine and cancer, after finding a six-fold increase in cancer incidence among patients in the treatment.
Researchers speculated that insulin glargine could cause metabolic changes that might accelerate the growth of pre-existing tumours.
But prescribing Metformin in addition to insulin glargine appeared to have a protective effect, cancelling out the risk of cancer at lower insulin doses and halving it at the highest doses.
In response to the trial’s findings, Sanofi-Aventis, manufacturer of insulin glargine, announced it will launch a new probe that will ‘provide methodologically robust research that will contribute to the debate over insulin safety’.
In July, the European Association for the Study of
diabetes (EASD) made ‘an urgent call for more research into a possible link between insulin glargine and increased risk of cancer’, following evidence from studies in Germany, Sweden and the UK.
The latest study, presented in a stormy session last week at the EASD annual meeting in Vienna, analysed cancer incidence at more than 300 GP practices in the UK.
Researchers analysed data from 5,000 patients with type 2 diabetes on a combination of insulin glargine and metformin, and over 30,000 on insulin alone.
Crude cancer rates at the highest doses of both drugs were 60 per 1,000 person-years in patients treated with insulin alone compared with 10 with metformin alone. The rate fell to 34 cancers per 1,000 person-years when metformin treatment was added.
After adjusting for age, gender and smoking status, insulin monotherapy was associated with a 5.7-fold increase in the risk of any cancer, which fell to 3.2 when metformin was also prescribed.
Study leader Dr Craig Currie, research fellow at the University of Cardiff school of medicine, told delegates: ‘The results are highly statistically valid. There was a dose-dependent association between insulin glargine and cancer in type 2 diabetes – supporting the principle of causality.’
EASD president Professor Ulf Smith said: ‘The epidemiological relationship is clear but association is not the same as cause. What we’re worried about is in patients with already existing cancers their growth may be accelerated in the presence of insulin glargine.’
But Dr Jay Skyler, associate director of the Diabetes Research Institute in Miami and a consultant for Sanofi-Aventis, insisted: ‘