FGF21 and type 2 diabetes mellitus: Genetic prediction of FGF-21 (OR = 0.87, 95% CI = 0.81-0.93, P-value = 9.77e-05) and hGDNF (OR = 0.96, 95% CI = 0.95-0.98, P-value = 2.77e-05) per a 1-SD increase correspondingly reduced the risk of type 2 diabetes.