CST3 and metabolic syndrome: Furthermore, even if our findings, adjusted for known MetS risk factors in the entire MDC-CC-reexamination cohort, indicates that high levels of cystatin C measured in plasma might serve as a predictor of future MetS, a causal involvement of cystatin C in the etiology of MetS or indeed diabetes seems unlikely since genetic elevation of plasma cystatin C (e.g. major allele C of rs13038305) was not related to altered risk of these diseases.