GLP1R and type 2 diabetes mellitus: VIP - vasoactive intestinal peptide. HDL - high-density lipoprotein. LDL - low-density lipoprotein. RYGB - Roux-en-Y gastric bypass. LSG - laparoscopic sleeve gastrectomy. NGT - normal glucose tolerance. IGT - impaired glucose tolerance. T2D - type 2 diabetes. GLP-1 - glucagon like peptide 1. OGTT - oral glucose tolerance test.