Objective: Proinflammatory cytokine IL-1beta is capable of decreasing insulin-induced glucose transport. Therefore, we hypothesized that genetic variation in the IL-1 gene family is associated with measures of glucose homeostasis and diabetes.
Design and outcome measures: Fifteen haplotype-tagging single-nucleotide polymorphisms in the IL-1alpha, IL-1beta, and IL-1 receptor antagonist genes were determined in a Finnish population survey (n = 6771). Glucose and insulin concentrations were measured, and indices of insulin resistance and beta-cell function were calculated using the homeostasis model assessment. Two-hour oral glucose tolerance tests were carried out on a subsample of 1390 participants. Associations with prevalent diabetes were tested for replication in a sample of European myocardial infarction survivors (n = 972).
Results: The minor allele of the IL-1beta rs1143634(G-->A) was associated with higher blood glucose than the major allele: 5.37, 5.41, and 5.48 mmol/liter for the GG, AG, and AA genotypes, respectively (multivariate adjusted P for trend <0.0001; Bonferroni corrected P = 0.00096). The 2-h glucose was also higher (6.45 and 7.20 mmol/liter for the GG vs. AA; P = 0.003, Bonferroni corrected P = 0.045). The haplotype ACG of rs1143634, rs3917356, and rs16944 associated with higher glucose, higher homeostasis model assessment for insulin resistance index, higher 2-h insulin, and prevalent diabetes (adjusted rate ratio = 1.54; 95% confidence interval = 1.03-2.30; P = 0.037). The association with prevalent diabetes was replicated among European myocardial infarction survivors (rate ratio = 2.09; 95% confidence interval = 1.17-3.76; P = 0.013).
Conclusions: These results suggest that genetic variation in the IL-1 gene family is associated with measures of glucose homeostasis and prevalent diabetes.