Although disease duration and rheumatoid factor were not related to carbohydrate metabolism molecules, the presence of anticitrullinated peptide/protein antibody was negatively associated with insulin and C-peptide serum levels and HOMA2-%B, but it was positively correlated with DDP-4 levels (β coefficient 157 [95% CI 58–256] ng/ml, p = 0.002). Here, INS is linked to rheumatoid factor measurement.