Metabolic and systemic inflammation status in rheumatoid arthritis-fasting blood glucose as a primary predictor of rheumatoid arthritis risk: a cross-sectional study in Iran.

Background: This study investigated the relationship between metabolic factors (blood lipids and glucose) and inflammatory indicators (tumor necrosis factor-alpha [TNF-α] and high-sensitivity C-reactive protein [hs-CRP]), disease activity, and the rheumatoid arthritis (RA) risk.

Methods: Serum fasting blood glucose (FBG) and lipid profiles-including total cholesterol (Chol), triglycerides (TG), high-density lipoprotein (HDL), and low-density lipoprotein-were measured in 100 RA patients and 100 healthy individuals. Disease severity was assessed using the disease activity score 28. Inflammatory indicators (TNF-α and hs-CRP) were measured using the enzyme-linked immunosorbent assay method.

Results: In RA patients, serum FBG, TG, Chol/HDL, and TG/HDL were significantly elevated, whereas HDL levels reduced compared to healthy individuals. Multivariate analysis indicated that each unit increase in serum FBG, HDL, Chol/HDL, and TG/HDL was associated with a 64% increase (p<0.001), a 7% reduction (p=0.001), a 52% increase (p=0.007), and a 54% increase (p=0.001) in the odds of RA, respectively. Disease activity showed no correlation with metabolic factors (p>0.05). Among all metabolic factors studied, FBG had the largest area under the curve (0.981) (p<0.0001) for predicting RA. Across the total participant group, FBG, TG, and TG/HDL were positively associated with hs-CRP and TNF-α (p<0.05). HDL showed an inverse association with hs-CRP (p=0.008). Among RA patients specifically, TNF-α positively correlated with TG and TG/HDL, while hs-CRP correlated only with TG/HDL.

Conclusion: These findings indicate that increased FBG and Chol/HDL and decreased HDL may elevate RA risk by promoting systemic inflammation. Among these, elevated FBG may serve as the strongest predictor of RA risk.