A major new study from the UK has found that people newly diagnosed with type 2 diabetes (T2D) face a higher risk of developing certain obesity-related cancers, particularly cancers of the liver, pancreas, and bowel.
The research will be presented at the upcoming European Congress on Obesity (ECO 2025) in Malaga, Spain, and is one of the largest and most carefully designed studies on the topic to date.
The study was conducted by Owen Tipping and Professor Andrew Renehan from the University of Manchester and the National Institute for Health Research (NIHR) Manchester Biomedical Research Center, alongside their colleagues.
Previous studies have suggested links between T2D and higher cancer risk, but many had limitations due to confounding factors like obesity or early detection bias. This new study aimed to eliminate those weaknesses and provide more reliable results.
Using data from the UK Biobank, the researchers examined 23,750 people with new-onset T2D and compared them with 71,123 matched individuals without diabetes. Participants were matched by age, sex, and body mass index (BMI) to ensure the findings were not simply explained by differences in body weight or other demographic factors.
The study tracked participants over a median of five years, during which 2,431 new primary cancers were recorded in the T2D group, compared to 5,184 cases in the control group.
The results showed:
- A 48% higher risk of obesity-related cancers (ORCs) in men with T2D
- A 24% higher risk in women with T2D
These increases were independent of BMI, meaning that diabetes itself—not just excess weight—appeared to play a role in raising cancer risk.
The researchers looked specifically at obesity-related cancers, which include cancers of the liver, pancreas, bowel, breast (postmenopausal), endometrium (lining of the uterus), kidney, esophagus, stomach, thyroid, gallbladder, ovary, and a few others.
Key Findings:
- Liver cancer risk was almost four times higher in men and nearly five times higher in women with new-onset T2D.
- Pancreatic cancer risk rose by 74% in men and nearly doubled in women.
- Bowel cancer risk increased by 27% in men and 34% in women.
- There was no clear link between T2D and some cancers traditionally linked to obesity, such as postmenopausal breast and endometrial cancers in women.
The authors carefully adjusted their results for other possible factors, such as smoking, alcohol use, and the likelihood of a cancer being detected soon after a diabetes diagnosis, simply due to increased medical attention. This helped ensure the associations they found were more likely to be real, rather than caused by bias.
Why Does Diabetes Increase Cancer Risk?
The researchers suggest several biological explanations are being explored:
- Hyperinsulinemia (too much insulin in the blood) may encourage the growth of cancer cells.
- High blood sugar (hyperglycemia) and chronic inflammation might also play a role.
- Among these, insulin’s effect on promoting cell growth and division is seen as the most likely mechanism.
They also note possible sex-based differences in cancer risk. For example, men and women might respond differently to insulin or have different fat distribution patterns and hormone levels, which could affect cancer risk.
However, some of the observed differences may simply reflect the number of cases within the database and need more investigation.
Review and Analysis:
This study provides strong evidence that a new diagnosis of type 2 diabetes is linked to increased risk of several—but not all—obesity-related cancers, particularly in liver, pancreas, and bowel.
It’s important to note that the risk is not fully explained by obesity alone, which has been a major confounder in past studies. Even when body weight was accounted for, diabetes still appeared to increase cancer risk.
The study’s strengths lie in its large sample size, use of careful matching and adjustments for bias, and its focus on newly diagnosed T2D, which helps avoid confusion from long-standing illness or co-occurring conditions.
For people living with or newly diagnosed with T2D, this research underlines the importance of long-term cancer screening, especially for specific types of cancer. For doctors and researchers, it emphasizes the need for more targeted prevention strategies and further study into the biological mechanisms connecting diabetes to cancer.
In the future, this growing body of evidence could help shape new guidelines for cancer surveillance in people with type 2 diabetes—and possibly lead to earlier detection and better outcomes.
If you care about diabetes, please read studies about Vitamin D and type 2 diabetes, and to people with diabetes, some fruits are better than others.
For more health information, please see recent studies that low calorie diets may help reverse diabetes, and 5 vitamins that may prevent complication in diabetes.
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