In this analysis, log transformed serum irisin was inversely associated with pre-diabetes/T2D independent of age, sex, BMI, waist circumference, systolic blood pressure, triglycerides, and HDL cholesterol [OR (95 % CI); 0.60 (0.45–0.79), P < 0.001; model IV]. The gene discussed is FNDC5; the disease is type 2 diabetes mellitus.