Cancer risk in diabetes The use of insulin by diabetic patients has been linked with the emergence of cancer. A European study is examining the risks associated with insulin administration. Health © Thinkstock Diabetes is caused by an inability to produce sufficient insulin, the hormone required to balance sugar levels in the blood, or because the body does not adequately respond to the insulin that is produced. Treatment of this metabolic disorder very often entails the lifelong administration of insulin or insulin analogues. However, a number of studies have highlighted the risk of cancer development in diabetic patients using insulin. Meta-analyses of randomised clinical trials comparing different insulin analogues were too small to quantify the risks. As a result, the European Medicines Agency has urgently requested studies to investigate the risks of cancer in insulin users. The EU-funded CARING (Cancer risk and insulin analogues) initiative essentially responds to this need. First, by reviewing clinical and published evidence on the risk of cancer associated with diabetes. Second, by performing a multi-country observational study assessing cancer risk with the use of insulin (analogues). Additionally they will elucidate the biological mechanisms responsible for the adverse effects of insulin administration. Scientists are also investing to identify potential co-founders which influence the association between insulin and cancer risk. So far, the consortium has finalised protocols for studying (common study protocol) and analysing (common data model). Data were obtained from five different European countries (Denmark, Finland, the Netherlands, Norway, Sweden and the United Kingdom). These data sets will help portray the day-to-day assessment of dose and cumulative duration of insulin use. Breast cancer samples are also undergoing molecular analysis to provide gene expression and genetic profiling information. The CARING project has already published various systematic reviews on risks of different cancer types in diabetic patients as well as the use of insulin and insulin analogues. Study outcomes will provide important new knowledge on the safety of diabetic medication and will help shape decisions concerning the future regulation of insulin use. Keywords Cancer, diabetes, insulin, cancer risk, protocols, genetic profiling
