In a large multi-centre study published in 2025, researchers observed that people with type 2 diabetes who had used metformin long term were diagnosed with certain cancers less often than patients treated with other diabetes medications.
The finding did not claim prevention, but it was enough to revive an ongoing scientific debate.
A study that reopened the question
The Times of India reported on several observational studies indexed in PubMed Central showing lower rates of colorectal and liver cancer among long-term metformin users.
Similar patterns have appeared in earlier datasets, but the scale of the 2025 analysis brought renewed attention.
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Researchers stressed that the results show association rather than direct cause. Still, the consistency has raised a key question: why does metformin keep appearing in cancer-related research when many other diabetes drugs do not?
Why metformin stands apart
Metformin differs from insulin and some newer glucose-lowering treatments because it does not increase insulin levels.
Instead, it reduces glucose production in the liver and improves insulin sensitivity. High insulin levels are known to stimulate cell growth, a process that cancer can exploit.
This distinction has made metformin especially interesting as cancer research increasingly focuses on metabolism and inflammation rather than single, targeted compounds.
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Overlapping biology, clear limits
Type 2 diabetes and cancer share biological pathways, including chronic inflammation, obesity and altered energy use in cells.
Metformin appears to interact with these processes, potentially reducing conditions that support tumour growth.
Experts caution that metformin is not a cancer drug and should not be used for prevention outside diabetes care.
Clinical trials are now testing whether it could play a supportive role alongside standard cancer treatments. Until then, established measures like healthy weight, physical activity and screening remain central.
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Sources: The Times of India and Pubmed
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