In a nationwide US study of nearly 920,000 overweight or obese adults with type 2 diabetes, GLP-1 agonist users had a 13% lower risk of obesity-related cancers compared to users of other diabetes medications.
13% lower cancer riskGLP-1 agonist users had an adjusted hazard ratio of 0.87 for obesity-related cancers compared to users of other diabetes medications, based on nearly 920,000 patients
What the researchers found
GLP-1 agonist users had a significantly lower incidence of obesity-related cancer at 7.5 per 1,000 person-years versus 8.1 for other glucose-lowering drugs, translating to an adjusted hazard ratio of 0.87 (95% CI: 0.83–0.91). The association was consistent across all comparator drugs: HR 0.90 vs metformin, 0.88 vs DPP-4 inhibitors, 0.84 vs thiazolidinediones, 0.81 vs sulfonylureas, 0.73 vs SGLT2 inhibitors, and 0.70 vs insulin.
The risk reduction showed a dose-response relationship with body weight: overweight patients had an HR of 0.95 (not statistically significant), mild-to-moderate obesity had HR 0.90, and severe obesity had HR 0.82 (interaction P = 0.032). This suggests the cancer-protective association strengthens as obesity severity increases.
Why it matters
Obesity is a known risk factor for at least 13 types of cancer, and people with type 2 diabetes already face elevated cancer risk. If GLP-1 drugs — originally designed for blood sugar and weight management — also reduce cancer risk, it would represent a major additional benefit for the millions of people now taking these medications. This is one of the largest studies to date examining this association.
How the study worked
This was a retrospective nationwide cohort study using Merative MarketScan research databases covering US commercial and Medicare claims data. Researchers identified all overweight or obese adults aged 20–79 with type 2 diabetes who started GLP-1 agonists or other glucose-lowering drugs between January 2016 and June 2021. The primary outcome was diagnosis of any of 13 obesity-related cancer types. Analyses used adjusted hazard ratios controlling for confounders, with over 2 million person-years of follow-up.
What this study cannot tell us
This is an observational cohort study using insurance claims data, so it cannot prove that GLP-1 drugs directly cause cancer risk reduction — only that an association exists. Claims databases may have coding inaccuracies and cannot capture important confounders like diet, exercise, smoking, or family cancer history. The study period (2016–2021) predates widespread use of newer GLP-1 drugs like high-dose semaglutide. Follow-up time may be too short to capture cancers with long latency periods.
How to read the evidence
This is a large retrospective cohort study published in the Journal of the National Cancer Institute with nearly 920,000 patients and over 2 million person-years of follow-up. While its massive sample size and consistent results across multiple comparators strengthen the findings, it remains observational and cannot establish causation.
When this study was published
Published in 2025 using data through mid-2021, this study captures a period when GLP-1 drugs were less widely used than today. The findings are highly relevant to current discussions about the broader health benefits of GLP-1 agonists.
The bigger picture
As GLP-1 drugs like semaglutide and tirzepatide become some of the most prescribed medications in the world, understanding their effects beyond weight loss and blood sugar is critical. A growing body of evidence suggests these drugs may reduce cardiovascular events, kidney disease progression, and now potentially cancer risk. This study adds to the case that GLP-1 agonists may have broad protective effects, though whether the cancer benefit comes from weight loss itself, direct anti-inflammatory effects, or other mechanisms remains unclear.
Questions still open
- Is the cancer risk reduction driven by weight loss itself, or do GLP-1 drugs have direct anti-cancer effects independent of weight change?
- Would newer, more potent GLP-1 drugs like high-dose semaglutide or tirzepatide show even stronger cancer risk reductions?
- Does the cancer-protective association persist long-term, or does risk return if patients stop GLP-1 therapy?
Common questions
Does this mean GLP-1 drugs like Ozempic prevent cancer?
Which cancers were included in this study?
Read the original research
Association between glucagon-like peptidase 1 receptor agonist and obesity-related cancer in overweight or obese patients with type 2 diabetes: a nationwide cohort study.
Journal of the National Cancer Institute, 117(10), 2053-2061
Citation
Mao, Xianhua; Zhang, Xinrong; Henry, Linda; Cheung, Ka Shing; Yuen, Man-Fung; Cheung, Ramsey; Seto, Wai-Kay; Nguyen, Mindie H. (2025). Association between glucagon-like peptidase 1 receptor agonist and obesity-related cancer in overweight or obese patients with type 2 diabetes: a nationwide cohort study.. Journal of the National Cancer Institute, 117(10), 2053-2061. https://doi.org/10.1093/jnci/djaf163