Revisiting the markers interleukin-6 and glucagon-like peptide-1 for targeting low-grade inflammation in type 2 diabetes: a meta-analysis and our lab experience.

Aim: Type 2 diabetes (T2DM) manifests as pancreatic disorder as a consequence of low-grade systemic inflammation, attributed to upregulated levels of interleukin-6 (IL-6). This in turn is associated with a reduced incretin effect with lower circulatory GLP-1 levels. Therefore, its important to monitor the circulating IL-6 and GLP-1 levels for better management and outcomes in T2DM patients.

Methods: Limited studies being available in literature on circulating concentrations of GLP-1 and IL-6 in T2DM patients, a meta-analysis was conducted by identifying 1558 studies from 3 databases. As per inclusion and exclusion criteria, the studies were screened for the 2-markers.Forest plots were drawn for standardized mean differences and median values were deduced from the datasets. In parallel, analysis was conducted to ascertain the expression levels of the markers by ELISA (n = 52 T2DM patients) in real time.

Results: The meta-analysis showed a significant (p < 0.01) standardized mean difference of 3.82 and 1.04 for IL-6 and GLP-1 respectively. The median values obtained from analysis for IL-6 were 26.50 pg/ml which were higher than the controls downregulated levels of GLP-1(8.77 pg/ml) were noted. The above findings are corroborated by the results of our experimental analysis with IL-6 concentrations at 11.603pg/ml and GLP-1 at 13.05pg/ml.

Conclusion: The study highlights that systemic concentrations of IL-6 and GLP-1 correspond to a persistent low-grade inflammation and decreased incretin effect in T2DM patients which manifest as pancreatic β-cell dysfunction. The expression of the markers is inversely correlated and monitoring their levels is clinically important for targeting them through their potential antagonists thus reducing the risk of complications, thereby improving the quality of life of the patients.