Serum interleukin-1 and interleukin-6 are correlated neither with oxidized low density lipoprotein, nor with low-grade inflammation in patients with type 2 diabetes

Abstract

In vitro studies have shown that oxidized, low density lipoprotein (ox-LDL) stimulates macrophages to release interleukin-6 (IL-6) and interleukin-1β (IL-1β). In this study, we aimed to investigate the correlation between ox-LDL and IL-6 and IL-1β levels in the peripheral circulation of patients with type 2 diabetes, and normal controls. We measured serum high sensitivity CRP (hs-CRP) levels in order to define basal inflammation in patients and controls. A total of 40 patients with type 2 diabetes, and 40, age, sex, and body mass index (BMI) -matched healthy adults were enrolled in the study. Fasting blood sugar (FBS), lipid profile, creatinine, ox-LDL, IL-6, IL-1β and hs-CRP levels were measured. Patients with type 2 diabetes had higher serum FBS, HbA1C, high density lipoprotein cholesterol, LDL, ox-LDL/LDL ratio and hs-CRP levels than controls. The higher serum ox-LDL/LDL ratio in patients with type 2 diabetes remained significant after multiple adjustments for age, BMI, FBS and HbA1C, (0.65 [0.59-0.71] vs 0.49 [0.41-0.56]; p<0.001) using general linear models. Serum IL-1β levels were significantly higher in women than in men with type 2 diabetes; this was not the case in controls. Postmenopausal women in patient and control groups had higher serum IL-6 levels than premenopausal women. There was no significant correlation between serum ox-LDL, ox-LDL/LDL ratio, IL-6, IL-1β and hs-CRP levels in patients with type 2 diabetes. Inflammatory cytokines such as IL-1β and IL-6 lose their discriminatory power with respect to chronic inflammation in patients with type 2 diabetes.