New Delhi: Cancer and diabetes — two of the world’s most common long-term illnesses — are now understood to be more closely linked than most people realize. As global cases of Type 2 diabetes surge past half a billion (580 million) people, new studies are shedding light on how the condition may also shape cancer risk.
According to The Cancer Atlas, cancer remains one of the leading causes of early death worldwide, responsible for nearly a third of all premature deaths among adults aged 30 to 69. At the same time, experts estimate that almost half of all cancer deaths could be prevented through healthier lifestyles, early detection, and better public health policies.
But it is diabetes that is increasingly drawing attention from cancer researchers.
A landmark study published in The Lancet Diabetes & Endocrinology has estimated that Type 2 diabetes alone accounted for over 2% of all new cancer cases globally — rising to nearly 6% when combined with high BMI.
“Our analysis suggests that the metabolic disturbances driving Type 2 diabetes also contribute meaningfully to cancer development,” explained author of the Lancet study. “This connection is not simply the result of shared lifestyle factors — it reflects genuine biological links.”
Why Is Diabetes Connected To Cancer?
Scientists point to a combination of hormonal and inflammatory changes. Persistently high insulin levels, chronic low-grade inflammation, and long-term elevated blood sugar can create conditions that encourage tumour growth.
A newly published 10-year longitudinal analysis adds another layer, suggesting cancer risk may rise even earlier. “We found signs that elevated cancer risk begins during pre-diabetes — well before a formal diabetes diagnosis,” the Lancet study noted.
Accurate data, however, remain a hurdle. A 2025 retrospective review from Leeds, UK, found that nearly one in five cancer patients with diabetes were not identified through standard hospital coding systems. Such gaps may mean the diabetes-cancer connection is even stronger than currently estimated.
For years, researchers hoped the diabetes drug metformin might offer cancer-protective benefits. But rigorous randomized trials have largely failed to show meaningful improvements in cancer outcomes.
Attention has now shifted to GLP-1 receptor agonists — the same drugs revolutionising diabetes and obesity treatment worldwide. Recent observational studies suggest these medications may improve survival in cancer patients, and a new JAMA Oncology analysis found reduced risk of several cancers among people with obesity taking GLP-1 drugs. However, the same study noted a possible increase in kidney cancer risk, highlighting the need for longer and more detailed trials.
Human Burden Beyond Biology
Medical experts stress that numbers alone cannot capture the emotional and psychological toll experienced by people living with both conditions.
Managing diabetes often involves daily monitoring, lifestyle shifts, and regular clinical visits. Combining that with cancer treatment can overwhelm even the most resilient patients. Worryingly, several studies show that people with diabetes are less likely to attend cancer screening appointments — meaning cancers may be discovered later, when they are harder to treat.
Health experts argue that it is time for more integrated services that treat patients, not just conditions. “As multi-morbidity becomes the norm rather than the exception, health systems must evolve—clinically, emotionally, and logistically,” the Lancet researchers concluded. “Supporting patients living with both diabetes and cancer requires coordinated care, early screening, and accessible mental-health support.”
For now, the message to the public is clear: healthy lifestyle choices, regular screening, and early management of diabetes risk can make a real difference — not only for diabetes itself, but possibly for cancer prevention too.