Role of glucagon-like peptide 1 (GLP-1) and its association with inflammatory markers in the pathogenesis of type 2 diabetes mellitus

Background: Diabetes mellitus is a multifactorial disease associated with hyperglycemia and increased risk of progression of vascular complications. Stimulation of insulin secretion by the incretin hormone glucagon-like peptide 1 (GLP-1) has been found to be diminished in hyperglycemia. We hypothesized that this impairment is due to defect at the receptor level induced by the diabetic state. Inflammatory markers like TNF-α and IL-6 plays a potential role in the pathogenesis of T2DM. Therefore, the present study aims to evaluate whether GLP-1 plays a role in the development of T2DM by modulating the balance between pro and anti-inflammatory markers. Material and methods: A total of 60 subjects were recruited in this study among them 30 were T2DM cases and 30 were healthy controls. m-RNA expression and protein level of GLP-1 receptor, TNF-α and IL-6 in peripheral blood lymphocytes were determined by real time PCR and ELISA respectively. Results: We observed plasma level of GLP-1 was significantly lower in diabetic subjects while serum level of IL-6 and TNF-α were significantly higher level in diabetic subjects (p < 0.05). We found significant down regulation of GLP-1 receptor m-RNA expression in diabetic subjects while expression level of IL-6 and TNF-α were 5.8 and 4 folds respectively higher in diabetic subjects. We found significant negative correlation of m-RNA expression of GLP-1 with protein level while IL-6 and TNF-α showed significant positive correlation. Conclusion: Inflammation plays an important role in the pathogenesis of diabetes mellitus and low GLP-1 levels may promote expression of inflammatory markers due to lack of anti-inflammatory effects of GLP-1