Circulating Fetuin-A and Risk of Type 2 Diabetes: A Mendelian Randomization Analysis.

Fetuin-A, a hepatic-origin protein, is strongly positively associated with risk of type 2 diabetes in human observational studies, but it is unknown whether this association is causal. We aimed to study the potential causal relation of circulating fetuin-A to risk of type 2 diabetes in a Mendelian Randomization study with SNPs located in the fetuin-A-encodingAHSGgene. We used data from eight European countries of the prospective EPIC-InterAct case-cohort study including 10,020 incident cases. Plasma fetuin-A concentration was measured in a subset of 965 subcohort participants and 654 cases. A genetic score of theAHSGSNPs was strongly associated with fetuin-A (28% explained variation). Using the genetic score as instrumental variable of fetuin-A, we observed no significant association of a 50 µg/ml higher fetuin-A concentration with diabetes risk (HR 1.02 [95%-CI 0.97, 1.07]). Combining our results with those from the Diabetes Genetics Replication And Meta-analysis (DIAGRAM) consortium (12,171 cases) also did not suggest a clear significant relation of fetuin-A with diabetes risk. In conclusion, although there is mechanistical evidence for an effect of fetuin-A on insulin sensitivity and secretion, this study doesn't support a strong, relevant relationship between circulating fetuin-A and diabetes risk in the general population