The effects of Apelin and Omentin on insulin resistance in patients with systemic lupus erythematosus and rheumatoid arthritis

Rheumatoid arthritis (RA) and Systemic lupus erytematosus (SLE) are autoimmune, chronic inflammatory diseases. Although the different pathogenesis in both disorders, insulin sensitivity reduces due to some inflamatory mediators. There is a strong relationship between insulin secretion and obesity associated adipokine apelin. It is known that insulin stimulates the apelin in adipocyte and apelin increases the glucose utilisation and inhibits insulin secretion. Omentin, a secretory glucoprotein, increases insulin stimulated glucose transport and insulin sensitivity. In this study we aimed to determine apelin and omentin levels and the association between these adipocytokines and disease phenotypes and insulin resistance in RA and SLE patients.This study comprises 34 RA, 32 SLE patients and 28 healty control (HC) subjects. In these groups addition to routine blood parameters we studied serum insulin, C-peptide, apelin and omentin levels. We determined the insulin resistance by Homeostasis Assesment For Insulin Resistance (HOMA-IR) method.In RA group, insulin and HOMA-IR levels were higher than both SLE (p<0.001) and HC (p<0.01) groups and C-peptide levels were higher than only HC group (p<0.05). Although apelin levels were similar in three groups, when adjusted with ANCOVA for age, apelin levels of SLE group was higher than HC group (p<0.04). Omentin levels of RA and SLE groups were both higher than HC group (p<0.05 and p<0.001 respectively).High levels of omentin in RA patients does not prevent the ınsulın resistance but on the other hand increased levels of apelin in SLE patients are seemed to be associated with insulin sensitivity.Key words; Rheumatoid arthritis, Systemic lupus erytematosus, insulin resistance, apelin, omentin