This study does something most do not: it publishes its results as absolute risk differences rather than as ratios. That decision is why the numbers look small, and it is why they are useful — a hazard ratio on a rare cancer tells you almost nothing about how many people are involved, which is the gap a relative figure always leaves.
What was compared
Adults with type 2 diabetes starting a GLP-1 drug in one academic center’s clinical research network between 2010 and 2025, set against new users of metformin, insulin, SGLT2 inhibitors, DPP-4 inhibitors and sulfonylureas. [1] The primary outcome was a first diagnosis of hepatocellular carcinoma, the commonest form of liver cancer, over five years.
The numbers
Against insulin, five-year liver cancer risk was 0.52 percentage points lower, 95% CI 0.35 to 0.74. Against sulfonylureas, 0.39 points, 95% CI 0.13 to 0.64. Against metformin, 0.37 points, 95% CI 0.08 to 0.59. Against DPP-4 inhibitors, 0.37 points, 95% CI 0.06 to 0.70.
Per-protocol analyses, which account for whether people kept taking the drug, were stronger — which is expected, and is also why who keeps taking it is never a neutral variable. Results held across subgroups, sensitivity analyses and individual agents.
Why four comparators matter
The estimates against metformin, insulin, DPP-4 inhibitors and sulfonylureas sit inside a narrow band, between 0.37 and 0.52 points.
That consistency is the strongest thing here. Confounding by who gets prescribed what tends to produce a large gap against a weak comparator and a small one against a strong one — which is exactly the pattern that made another study distrust its own mortality result. Four comparators agreeing is a different shape.
What is not established
Survival. A secondary analysis looked at death after a liver cancer diagnosis and the authors describe it as limited by small sample sizes, inconclusive and exploratory, suggesting a potential benefit without demonstrating one.
Nothing in this is a reason to take a GLP-1 drug for cancer prevention, and nobody sells them for that. It sits alongside what these drugs do to a liver more generally — where the fatty liver findings are stronger and the outcomes further away.