GLP-1 Drugs and the Liver: How Incretin-Based Therapies May Treat Fatty Liver Disease

GLP-1 receptor agonists have shown promise in treating MASH (formerly NASH) in phase II trials and are now in phase III testing. Newer dual and triple agonists combining GLP-1 with glucagon and/or GIP activity have demonstrated improvements in weight, insulin resistance, and non-invasive liver markers. However, it remains unclear whether these drugs act directly on liver disease or primarily work through upstream weight loss and metabolic improvements. The authors suggest that combining gut hormone agonists with agents that directly target fibrosis (like FGF21 or pan-PPAR agonists) may be the most effective strategy.

This is a narrative review article that synthesizes evidence from published clinical trials (phase IIa, IIb, and early phase III) of GLP-1 receptor agonists and multi-agonist peptides in patients with MASH. It evaluates both the direct and indirect mechanisms of action and discusses combination therapy strategies.

MASH is a leading cause of liver disease worldwide, driven primarily by obesity and insulin resistance. The GLP-1 drug class — including semaglutide and tirzepatide — represents one of the most promising therapeutic approaches, but the field is still working out which combinations work best. This review maps the current landscape of incretin-based liver therapies and identifies the key open questions that will shape clinical trials for years to come.

The explosion of GLP-1 drugs for weight loss and diabetes has opened an unexpected therapeutic frontier: liver disease. MASH affects hundreds of millions of people globally and currently has very few approved treatments. If incretin-based therapies prove effective — especially in combination with anti-fibrotic agents — it would represent one of the most significant expansions of the GLP-1 drug class beyond its original metabolic indications.

As a narrative review, this paper does not perform quantitative analysis or meta-analysis of the trials discussed. The optimal ratios of GLP-1, GIP, and glucagon agonism in multi-agonist drugs remain unresolved. The review acknowledges significant uncertainty about whether GIP agonism or antagonism is the better approach, and notes that combination therapies bring cumulative side-effect and cost concerns.