The finding is based on data from 4.03 million local diabetic patients, including 4 million who had their blood glucose data recorded in the Hong Kong Diabetes Surveillance Database from 2000 to 2019, and 30,000 treated at the Prince of Wales Hospital from 1995 to 2019.

With 537 million diabetic patients worldwide, one in eight Hongkongers suffers from the chronic disease, 25 percent of whom eventually die of cancer.

CUHK chair professor of medicine and therapeutics department Juliana Chan Chung-ngor said patients with diabetes have up to three times higher risk of developing cancer than other patients, especially in their liver, colon and rectum, pancreas, breast and uterus.

“Patients with suboptimal control of diabetes, especially in the presence of obesity, have an abnormal internal environment including low-grade inflammation which can promote cancer growth,” Chan said.

Statistics have indicated that 60 percent of diabetic patients were diagnosed with cancer after 20 years of diabetes history, most of whom had colorectal, liver and breast cancers.

People with high HVS, which measures the average blood glucose control, have a 15 percent higher possibility of developing cancer.

Obese patients with high glucose-covered red blood cells are 50 percent more likely to suffer from cancer.

However, diabetic patients treated with a common blood pressure lowering drug RASi are 50 percent less prone to cancer.

RASi was found to have prevented 2.2 cancer deaths, 6.3 all-cause deaths and 2.6 cancer developments per 1,000 diabetic patients using the drug each year.

Assistant professor from the department of medicine and therapeutics Elaine Chow Yee-kwan, who took part in the research, said: “In Hong Kong, only 50 percent of patients were treated with this class of drug.”

“Our novel data suggest that this drug class might lower cancer risk possibly by reducing the harmful effects of Ang II (a hormone that increases blood pressure and stimulates cell growth) on cancer growth.”