Association between IL-1B (-511)/IL-1RN (VNTR) polymorphisms and type 2 diabetes: a systematic review and meta-analysis

Interleukin-1 (IL-1) plays an essential role in the immune pro-inflammatory process, which is regarded as one of many factors in the development of type 2 diabetes mellitus (T2DM). Several case-control studies have illustrated the association of the IL-1B (-511) (rs16944, Chr 2:112,837,290, C/T Intragenic, Transition Substitution) and IL-1RN (VNTR) (gene for IL-1 receptor antagonist, IL-1RA, 86 bp tandem repeats in intron 2) polymorphisms with T2DM risk. However, the results were inconsistent and inconclusive. We performed a meta-analysis (registry number: CRD42021268494) to assess the association of the IL-1B (-511) and IL-1RN (VNTR) polymorphisms with T2DM risk. Random-effects models were applied to calculate the pooled ORs (odds ratios) and 95% CIs (confidence intervals) to test the strength of the association in the overall group and subgroups stratified by ethnicity, respectively. Between-study heterogeneity and publication bias were evaluated by the Q-test, I-2 statistic, Harbord test, and Peters test accordingly. Sensitivity analyses were also performed. A total of 12 publications evaluating the association of IL-1B (-511) and IL-1RN (VNTR) polymorphisms with the risk of T2DM development were included. The meta-analysis showed that IL-1RN (VNTR) was related to the increasing development of T2DM risk in the recessive model (OR = 1.62, 95% CI [1.09-2.42], P-het = 0.377, P-z = 0.018) and in the homozygous model (OR = 2.02, 95% CI [1.07-3.83], P-het = 0.085, P-z = 0.031), and the IL-1RN 2* allele was found a significant association with evaluated T2DM risk in all ethnicities (OR = 2.08, 95% CI [1.43-3.02], P-het < 0.001, P-z < 0.001) and in EA (OR = 2.01, 95% CI [1.53-2.66], P-het = 0.541, P-z < 0.001). Moreover, stratification by ethnicity revealed that IL-1B (-511) was associated with a decreased risk of T2DM in the dominant model (OR=0.76, 95% CI [0.59-0.97], P-het = 0.218, P-z = 0.027) and codominant model (OR = 0.73, 95% CI [0.54-0.99], P-het = 0.141, P-z = 0.040) in the East Asian (EA) subgroup. Our results suggest that the IL-1RN 2* allele and 2*2* homozygous polymorphism are strongly associated with increasing T2DM risk and that the IL-1B (-511) T allele polymorphism is associated with decreasing T2DM risk in the EA subgroup.