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The following is a summary of “Understanding the Role of the Complement System in Insulin Resistance and Metabolic Syndrome in Patients With Rheumatoid Arthritis,” published in the November 2024 issue of Rheumatology by Rodríguez-González et al. 

The complement system is linked to rheumatoid arthritis (RA), with insulin resistance and metabolic syndrome (MetS) common in affected patients. 

Researchers conducted a retrospective study to explore the link between the complement system, insulin resistance, and MetS in patients with RA. 

They recruited 339 nondiabetic patients with RA and assessed functional assays of the three complement pathways. Serum levels of complement components (C1q, lectin, C2, C4, C4b, factor D, properdin, C3, C3a, C5, C5a, C9, factor I, and C1 inhibitor) were measured. Insulin resistance and β-cell function were evaluated using the homeostatic model assessment, and MetS criteria were applied. Multivariable linear regression analysis explored the association between the complement system and insulin resistance. 

The results showed several complement elements, but not functional tests, correlated with higher insulin resistance and β-cell function. However, these associations were lost after adjustment for confounders, while MetS remained linked to higher levels of C1q, C4, C3, properdin, and factor I. 

They found a positive correlation between the complement system and metabolic syndrome in nondiabetic patients with RA, independent of insulin resistance factors. 

Source: jrheum.org/content/51/11/1069