GCG and Hyperglycemia: Preclinical studies have found that GLP-1 may be able to protect the kidneys from hyperglycemia-induced oxidative stress by activating the cyclic adenosine monophosphate–protein kinase A (cAMP–PKA) pathway, leading to an increase in cAMP and a subsequent reduction in the levels of nicotinamide adenine dinucleotide phosphate (NAD(P)H) oxidase [20,23].