title: Interleukin-6 gene polymorphism and insulin sensitivity.
abstract: Type 2 diabetes and the insulin resistance syndrome have been hypothesized to constitute manifestations of an ongoing acute-phase response. We aimed to study an interleukin-6 (IL-6) gene polymorphism in relation to insulin sensitivity (IL-6 is the main cytokine involved in an acute-phase response). Subjects homozygous for the C allele at position -174 of the IL-6 gene (SfaNI genotype), associated to lower plasma IL-6 levels, showed significantly lower integrated area under the curve of serum glucose concentrations (AUCglucose) after an oral glucose tolerance test, lower blood glycosylated hemoglobin, lower fasting insulin levels, lower total and differential white blood cell count (a putative marker of peripheral IL-6 action), and an increased insulin sensitivity index than carriers of the G allele, despite similar age and body composition. A gene dosage effect was especially remarkable for AUCglucose (6.4 vs. 9.3 vs. 9.7 mmol/l in C/C, C/G, and G/G individuals, respectively). The serum concentration of fully glycosylated cortisol binding globulin (another marker of IL-6 action), suggested by concanavalin A adsorption, was lower in C/C subjects than in G/G individuals (32.6+/-2.9 vs. 37.6+/-4.6 mg/l, P = 0.03). In summary, a polymorphism of the IL-6 gene influences the relationship among insulin sensitivity, postload glucose levels, and peripheral white blood cell count.
authors.affiliation: Unitat de Diabetologia, Endocrinologia i Nutricio, University Hospital of Girona Dr Josep Trueta, Spain. endocrino@htrueta.scs.es
authors.forename: J M
authors.initials: JM
authors.lastname: Fernández-Real
authors.forename: M
authors.initials: M
authors.lastname: Broch
authors.forename: J
authors.initials: J
authors.lastname: Vendrell
authors.forename: C
authors.initials: C
authors.lastname: Gutiérrez
authors.forename: R
authors.initials: R
authors.lastname: Casamitjana
authors.forename: M
authors.initials: M
authors.lastname: Pugeat
authors.forename: C
authors.initials: C
authors.lastname: Richart
authors.forename: W
authors.initials: W
authors.lastname: Ricart
mesh_terms: D000328:Adult; D000483:Alleles; D019540:Area Under Curve; D001786:Blood Glucose / Q000032:analysis; D005215:Fasting / Q000097:blood; D005260:Female; D018628:Gene Dosage; D005951:Glucose Tolerance Test; D006442:Glycated Hemoglobin / Q000032:analysis; D006720:Homozygote; D006801:Humans; D007328:Insulin / Q000097:blood / Q000502:physiology*; D007333:Insulin Resistance / Q000235:genetics*; D015850:Interleukin-6 / Q000097:blood / Q000235:genetics*; D007958:Leukocyte Count; D008297:Male; D008875:Middle Aged; D011110:Polymorphism, Genetic; D011446:Prospective Studies
chemical_list: D001786:Blood Glucose; D006442:Glycated Hemoglobin; D007328:Insulin; D015850:Interleukin-6