People with obesity, prediabetes, or type 2 diabetes tend to have higher levels of a hormone called FGF-21 in their blood compared to healthy-weight people, and the more severe the metabolic issue, the higher the level seems to go.

What we've found so far is that people with obesity, impaired glucose tolerance, or type 2 diabetes tend to have higher levels of a hormone called FGF-21 in their blood compared to those with healthy body weights [1]. The evidence we've reviewed leans toward this pattern, with 42.0 supporting assertions and none refuting it. FGF-21, or fibroblast growth factor 21, is a hormone involved in how the body manages energy, sugar, and fat. Our analysis of the available research shows that levels of this hormone are generally elevated in individuals dealing with metabolic challenges like obesity or insulin resistance [1]. What’s more, the evidence suggests a trend: the worse the metabolic condition, the higher the FGF-21 levels appear to be [1]. This includes people with prediabetes and those with full type 2 diabetes. We don’t yet know whether higher FGF-21 levels are the body’s attempt to fix metabolic problems or if they’re a sign the system is struggling. But what we can say is that, based on what we’ve reviewed so far, elevated FGF-21 is consistently linked with these conditions. It’s important to note that our current analysis only reflects what has been reported in the studies we’ve examined. We’re not concluding that this hormone causes any condition, nor are we saying it’s a definitive marker for disease. More research may refine or change this picture over time. Practical takeaway: If you have obesity or blood sugar issues, your body might be producing more FGF-21. This could be a signal your metabolism is under stress — but it’s not something to panic about. It’s just one piece of a much larger puzzle.