10% of the 320.000 Danes who live with diabetes have type 1 diabetes. New research conducted by Steno Diabetes Center in collaboration with the Danish Cancer Association and a number of international partners show that persons with type 1 diabetes have an increased risk of a number of cancer types including cancers of the liver, pancreas, uterus, ovaries and kidney. The findings also show a reduced risk of other cancer types, including prostate and breast cancer.
The study analysed more than 9,000 cancer cases in type 1 diabetes patients diagnosed across five countries including Denmark. It is the first scientific study to investigate the prevalence of cancer among people with type 1 diabetes.
”The excess incidence of cancer among people with type 1 diabetes is only few percent men if we look at types of cancers we see an increased prevalence especially in the pancreas and liver where the risk is up to the double. On the other hand there is a decreased prevalence of prostate and breast cancer of around 40% for prostate cancer and 10% for breast cancer among people with type 1 diabetes”, says senior researcher at Steno Diabetes Center Bendix Carstensen and adds that the excess cancer incidence in people with type 2 diabetes who use insulin is 20-25%.
According to the researchers there is not a clear-cut explanation why persons with type 1 diabetes have a higher cancer prevalence but the answer might be that the disease is detected in conjunction with the diabetes diagnosis. De new results does not prompt a change in the current guidelines.
Speaks against link between insulin and cancer
The study also reported that cancer incidence was highest shortly after diagnosis of diabetes.
"After approximately 20 years of having type 1 diabetes we see that the cancer incidence declines to the level of the general population. That is interesting because all persons with type 1 diabetes receive insulin treatment which is not the case in type 2 diabetes. If insulin treatment was a major cancer risk factor, the excess cancer incidence among people with type 1 diabetes would be expected to increase over the years. However, we have found the opposite and that speaks against linking use of insulin with cancer”, says Bendix Carstensen.
The study analysed 9,149 cancer cases in type 1 diabetes patients diagnosed across five countries, using data from five nationwide diabetes registers: Denmark, Australia, Finland, Scotland and Sweden. By linking these data with those in national cancer registries, the authors were able to compare the cancer incidence among people with type 1 diabetes to that of the general population.
The study is funded by the European Foundation for the Study of Diabetes (EFSD) under the European diabetes research association EASD. The results been published in the recognised scientific journal Diabetologia