GDF15 and diabetes mellitus: The association tended to be less significant with increasing age: multivariate-adjusted HRs for diabetes per SD increase of GDF-15 were 1.24 (95% CI 1.08, 1.42), 1.19 (95% CI 1.00, 1.41) and 1.04 (95% CI 0.89, 1.23) for participants aged ≤55, 56–60 (>55 and ≤60) and >60 years, respectively.