FGF21 and diabetes mellitus: Despite of FGF-21 being a risk factor for diabetes, recent animal study and clinical trials in humans have shown beneficial effects of exogenous FGF-21 on lipid profile, levels of adiponectin, fasting insulin and glucose in obese patients with diabetes [30–32], suggesting FGF-21 may also serve as a potential therapeutic agent for treating type 2 diabetes in humans.