Relationship of adipokines and non-esterified fatty acid to the insulin resistance in non-diabetic individuals

Background: Altered secretion of adipokines and non-esterified fatty acid (NEFA) seems to play a pivotal role in the abdominal obesity-related insulin resistance (IR). Aim: To determine semi-quantitatively the impact of serum NEFA, interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), leptin, adiponectin, and resistin levels on IR measured by homeostasis model assessment (HOMA-IR). Material/subjects: Seventy-four Caucasian subjects forming 3 age-, and sex-matched groups were included into the study [Group 1 and 2: non-diabetic obese patients, no.= 25, body mass index (BMI): 28–39.9 kg/m2, no.=25, BMI≥40 kg/m2, respectively, and Group 3: 24 healthy, normal weight control subjects]. Methods: Serum levels of NEFA and adipokines as well as other metabolic variables including HOMA-IR were measured. Results: HOMA-IR was associated positively with BMI, waist circumference, serum NEFA, leptin, IL-6, and TNF-α levels, negatively with adiponectin, with no significant relation to resistin. In multiple regression analyses, of these factors leptin was a strong, IL-6 and adiponectin were weak independent predictors of HOMA-IR, while the others were not significant determinants of HOMA-IR. However, even together, they explained only 35–36% of variance of HOMA-IR. Conclusions: Although IR has associations with many of the investigated parameters, of these, only serum level of leptin, and in lesser degree IL-6 and adiponectin are independent determinants of the severity of IR. Moreover, even together they explain only a minority of variance IR.