Previous research has suggested a link between the presence of diabetes and a person's risk of cancer. Now, a large study in a Chinese population shows that type 2 diabetes is associated with an increased risk of cancer—though females and males seem to be more at risk of different forms.

Last week, Medical News Today reported on a study showing that people who have cancer and diabetes may have an increased risk that their malignant tumors will spread. The study, which explains the likely biological mechanism underlying this risk, was spurred by other research suggesting a link between diabetes and cancer.

Now, investigators—many from the Shanghai Jiao Tong University School of Medicine, in China—have published the results of an analysis conducted using the medical data of a large Chinese cohort. The research paper, the first author of which is Jiying Qi, appears in the Journal of Diabetes.

The researchers also note that their country has a very high prevalence of both diabetes and prediabetes, as reports have shown. The team identified 410,191 adults—aged between 20 and 99—who had a diagnosis of type 2 diabetes between July 2013 and December 2016. At that time, none of these people had cancer.

Qi and colleagues followed the medical records of these individuals through to December 2017, to see which people developed cancer and what form of cancer their doctors diagnosed.

Significantly higher risk of cancer

By the end of 2017, the researchers had identified 8,485 cases of cancer among the initial cohort, and the investigators soon realized that males with type 2 diabetes and females with the same condition had a higher risk of distinct types of cancer.

The researchers found that, among people with type 2 diabetes, males had a 34% higher risk of cancer than their healthy peers, and females had a 62% higher risk. Males with type 2 diabetes were more at risk of as many as 11 different forms of cancer, while females were more at risk of 13 different forms.

More specifically, males with type 2 diabetes had an 86% increase in the risk of prostate cancer compared with their healthy counterparts. They also had a significant risk of leukemia, skin cancer, thyroid cancer, lymphoma, kidney cancer, liver cancer, pancreatic cancer, lung cancer, colorectal cancer, and stomach cancer. However, males with the metabolic condition appeared to have a lower risk of developing esophageal cancer.

As for females with type 2 diabetes, they were most at risk for nasopharyngeal cancer, of which they had more than a two-fold risk. They also had a high risk of developing cancer of the liver, esophagus, thyroid, lungs, and pancreas, as well as lymphoma, uterine cancer, colorectal cancer, leukemia, breast cancer, cervical cancer, and stomach cancer. Females with type 2 diabetes, however, had a significantly lower risk of developing gallbladder cancer.

"The Shanghai Hospital Link Center has collected clinical information from the main general and specialized hospitals and created a centralized data repository for all residents in Shanghai since 2013," co-author Bin Cui explains regarding the data used in the study. "Based on this database, our research could be carried out smoothly and efficiently," he notes.

Following their current findings, the research team advises that relevant organizations should come up with better preventive strategies for cancer among people with type 2 diabetes.