Effect of Anti-TNF Therapy on Resistance to Insulin in Patients with Rheumatoid Arthritis

Objective: To evaluate the effect of anti-TNF therapy on resistance to insulin in patients with rheumatoid arthritis (RA) compared with patients with RA being treated with non-biological DMARDs. Methods: Inactive patients diagnosed with RA (ACR 1987 criteria) (DAS 28 2.6) were included, being treated with anti-tumor necrosis factor inhibitors (anti-TNF) (cases) and non-biological disease-modifying anti-rheumatic drugs (DMARD) (controls), without risk factors for insulin resistance (administration of steroids, body mass index > 25 kg/m2, diabetes mellitus or use of glucose lowering agents, systemic arterial hypertension or use of anti-hypertensive drugs, triglycerides > 150 mg/dl, hypercholesterolemia > 200 mg/dl, high-density lipoproteins 40 mg/dl in men and 50 mg/in women, or with lipids lowering agents, waist measurement > 88 cm in women and > 102 cm in men). We used HOMA (Homeostasis Model Assessment) to determine insulin resistance in both groups, HOMA being defined as >1 and sensitivity to insulin using QUICKI (Insulin Sensitivity Check Index), ≥0.38 being considered as normal. The Mann Whitney U was used for the statistical analysis. Results: A total of 28 patients, 15 being treated with non-biological DMARDs and 13 with anti-TNF therapy, were evaluated; 89.7%, of which were women. Average age: 43.5 (range 21 - 62); the average HOMA index of the non-biological DMARD group was 1.58 (range 0.7 - 5.4), compared with patients treated with anti-TNF therapy, 1.18 (range 0.2 - 4.3) (P = 0.5). The average QUICKI index was 0.36 (range 0.30 - 0.42) in patients treated with non-biological DMARD, compared with0.37 inpatients treated with anti-TNF therapy (range 0.30 - 0.51) (P = 0.8). Conclusion: Resistance to insulin manifested itself in both groups, although there was a greater trend of less insulin resistance and greater sensitivity in the anti-TNF group; this was probably not statistically significant due to the sample size.