A generalized additive model was used to assess the nonlinearrelationship between serum GGT levels and incident diabetesmellitus.
We conducted restricted cubic spline models to develop HR curvesto examine the possible nonlinear dose-response associationsbetween serum folate concentrations and mortality, which are alsoconducted in total, age-specific and gender-specific participants. Inthese models, folate status was used as a continuous variable withfour knots (5th, 35th, 65th and 95th) suggested by Harrell.
