Cancer Risk Higher With Type 1 Diabetes
Overall Increase Is Modest, but Study Shows Double the Stomach Cancer Risk
Nov. 2, 2003 -- People with type 1 diabetes are at increased risk for developing certain cancers, say Swedish researchers.
Researchers from Stockholm's Karolinska Institute found that people with type 1 diabetes had a modest overall increase in cancers compared with people without diabetes. But they had nearly double the risk for developing stomach and cervical cancer and almost three times the risk for developing cancer of the uterus.
The population-based study is published in the Dec. 3 issue of the Journal of the National Cancer Institute.
Difference Is No Surprise
Type 2 diabetes has been linked to an increased risk for cancers of the liver, pancreas, kidney, and uterus, but until now little has been known about the cancer risks associated with type 1 diabetes. Previous studies examining the question have been small and had short follow-up times.
In this study, lead researcher Kazem Zendehdel and colleagues used a Swedish national health registry to track cancer incidence over time among people with type 1 diabetes.
Study investigator Weimin Ye, MD, PhD, tells WebMD that it is no surprise that, with the exception of uterine cancer, the malignancies linked to type 1 diabetes differed from those associated with type 2 disease.
That is because the two diabetes types have different metabolic and hormonal characteristics. Type 2 diabetes is associated with increased circulating insulin levels, whereas type 1 patients tend to have very low or no circulating insulin levels. This increase in insulin is believed by many to play a role in certain cancers linked to type 2 diabetes, especially pancreatic cancer.
Obesity Also Implicated
"We thought we would see a difference in the cancer-risk profile in patients with type 1 diabetes, and that is what we found," Ye says. "The fact that we did not find an increase in pancreatic cancers suggests that circulating insulin is involved in the promotion of this cancer."
National Cancer Institute director of cancer prevention Peter Greenwald, MD, says while circulating insulin may play a role in pancreatic cancers associated with type 2 diabetes, obesity is also a likely cause. Obesity is a major cause of type 2 diabetes, and a recent study showed that obesity plays a role in 20% of all cancers in women and 14% of cancers in men.
"Obesity substantially increases the risk of (type 2) diabetes and many types of cancer," he tells WebMD. "So it stands to reason that there would be a link between the two."