The risk of suffering from cancer is exacerbated in the 10-year period before diabetes diagnosis and the 3 months after diagnosis. In contrast, there is no association between these two conditions for the 10-year period after the diagnosis. Therefore, it is likely that untreated diabetes is a risk factor for cancer.
There is accumulating evidence supporting the relationship between type II diabetes and an increased risk of several cancers, including liver, pancreatic and endometrial cancers. However, this correlation might be attributable to an increase in health screening related to closer proximity with health care professionals, which occurs as a result of constant check-ups for diabetics.
The clinical study performed by a group of Canadian researchers evaluated this hypothesis by comparing the rate of cancer diagnosis in people with and without diabetes in different periods before or after diabetes diagnosis. Those periods were less than 10 years previous, less than 3 months after, or between 3 months and 10 years after the diagnosis of type II diabetes.
Their results published in the Cancer journal, showed that the risk of cancer is higher in the 10-year period prior to the diagnosis of diabetes. Among the 516,219 people with diabetes included in the trial, 9090 patients were diagnosed with cancer in this period while 7,466 were diagnosed in the control group containing the same number of individuals. This means that people with undiagnosed diabetes are 23% more likely to suffer from cancer within the 10-year period before diagnosis than the general population. This result supports the biological association between these conditions. Indeed, they share metabolic risk factors such as obesity and insulin resistance. Therefore, the association is likely to be due to common developing pathways, rather than a causality relationship.
In the 3-month period following diabetes diagnosis, the incidence of cancer was increased by 62%. In contrast, the incidence of cancer was similar with or without diabetes in the period between 3 months and 10 years after diagnosis. Therefore, there is also a probable bias due to the higher proximity to a health care professional in the period directly following diagnosis of diabetes.
Written By: Jean-Michel Bourget, PhD