KL and metabolic syndrome: After fully adjusting for potential confounders such as age, sex, race, education, BMI, waist, smoking status, alcohol intake, physical activity, CVD, hypertension, dyslipidemia, TG, TC, LDL-C, HDL-C, and eGFR, the bottom quartile of serum Klotho levels was used as a reference, revealing that subjects in the second to the fourth quartile were at a greater risk of diabetes.