Interleukin-6 (IL-6) and IGF-IGFBP system in children and adolescents with type 1 diabetes mellitus

Background: Some studies suggest that IL-6 is connected with glucose metabolism and insulin action, so like IGF-IGFBPs system it could play the role in diabetes etiopathogenesis. Aim: The aim of the study was therefore to test the hypothesis that in children and adolescents IL-6 is of importance for the etiopathogenesis of diabetes mellitus type I and that IL-6 is connected with carbohydrate metabolism and IGF-IGFBPs action. Methods: There were 49 patients with type 1 diabetes: 10 persons at onset diabetes and 39 with disease lasted at least 1 year and 33 age-matched healthy children included into the study. Serum IGF-I concentrations were measured by RIA; IGFBP-1 and IGFBP-2 by IRMA and IL-6 concentrations using quantitative ELISA immunoassays. HbA1c was measured by HPLC method. Multiple regression, ANOVA, and Student's t-test were used for statistical analysis. Results: IL-6 and IGF-I, IGFBP-1 and IGFBP-2 levels did not differ statistically significant between diabetic patients and controls. IL-6 concentrations were statistically higher at onset diabetes than in diabetic patients with long-term disease. IL-6 did not correlate with IGF-I and its binding proteins -1 and -2 in examined groups. At onset of disease IL-6 correlated with insulin requirement. There were not found correlations between IL-6 and HbA1c in diabetic groups. IGF-I positively correlated with age and growth in both groups and with IGFBP-2 in diabetic patients. IGFBP-2 correlated negatively with BMI in all examined groups. Conclusions: IL-6 might play a significant role in type 1 diabetes mellitus etiopathogenesis. It seems that IL-6 does not regulate IGF-IGFBP system in diabetic children and adolescents or IL-6 maybe cooperate with IGF-I, but their significant dependence on insulin action influences their mutual relationships.