GCG and Hyperglycemia: Further, previous studies indicate that the defect in GLP-1 secretion comes as a result of disease progression, likely due to a reduction of GLP-1 secretion [6, 26] following the presence of hyperlipidemia/hyperglycemia and glucolipotoxicity that may directly alter the function and viability of enteroendocrine cells secreting GLP-1 [13, 27].