GCG and rheumatoid arthritis: When investigating the metabolic markers, a stepwise increase was observed for active GLP-1 (p < 0.01 vs. HC) and GIP-1 (p < 0.001 vs. HC) and Leptin (p = 0.07 vs. HC) (Fig. 4C), suggesting these markers were already altered in ‘individuals at risk’ of developing RA.