New-onset type 2 diabetes linked to increased risk of some obesity-related cancers
New research to be presented at the European Congress on Obesity (ECO 2025, Malaga, Spain, 11–14 May) has revealed that a new diagnosis of type 2 diabetes is associated with an increased risk of developing certain obesity-related cancers. However, the study found that this link does not apply to all obesity-related cancers.
The research, led by Owen Tipping from the University of Manchester, UK, and Professor Andrew Renehan from the National Institute for Health Research (NIHR) Manchester Biomedical Research Centre, UK, aimed to address previous methodological limitations in studies examining the relationship between type 2 diabetes and cancer risk. The study was conducted using data from the UK Biobank.
The researchers conducted a matched cohort control study comparing individuals with new-onset type 2 diabetes (defined by the date of first reported non-insulin-dependent diabetes) to unexposed individuals. Each participant with type 2 diabetes was matched with three controls based on body mass index (BMI), age, and sex. The primary outcome measured was the incidence of obesity-related cancers, including cancers of the liver, pancreas, bowel, post-menopausal breast, endometrium, kidney, oesophagus, stomach, multiple myeloma, gallbladder, thyroid, meningioma, and ovary.
A total of 23,750 participants with type 2 diabetes were matched with 71,123 controls. Over a median follow-up period of five years, there were 2,431 new primary cancers among individuals with type 2 diabetes and 5,184 new primary cancers among controls.
The analysis revealed that new-onset type 2 diabetes was associated with a 48 per cent increased risk of obesity-related cancers in men and a 24 per cent increased risk in women. This effect was independent of BMI. However, no significant associations were found between new-onset type 2 diabetes and endometrial or post-menopausal breast cancer in women.
Among site-specific cancers, the study found:
A 27 per cent increased risk of bowel cancer in men and a 34 per cent increased risk in women.
A 74 per cent increased risk of pancreatic cancer in men and a near doubling of risk in women.
A near quadrupling of liver cancer risk in men and a nearly five-fold increase in women.
The researchers remain uncertain whether these differences between men and women are due to biological factors such as hormone levels, insulin sensitivity, and body fat composition or simply reflect variations in cancer incidence within the UK Biobank.
The study authors suggest that several mechanisms may explain the link between new-onset type 2 diabetes and certain cancers, including hyperinsulinaemia (high insulin levels), hyperglycaemia (high blood sugar levels), and chronic inflammation. Of these, hyperinsulinaemia is considered the most likely cause, as insulin can promote cell growth and proliferation, potentially increasing cancer risk.
The researchers conclude that while new-onset type 2 diabetes is associated with a higher risk of some obesity-related cancers, further research is needed to understand the underlying biological pathways.