Whereas glucose serum levels were not different between control subjects and patients, insulin (9.8 ± 6.5 vs. 13.0 ± 13.4 U/ml, p = 0.007) and C-peptide serum levels (1.53 ± 0.77 vs. 3.37 ± 2.94 ng/ml, p = 0.000) were found to be upregulated in patients with RA. This evidence concerns the gene INS and rheumatoid arthritis.