GCG and prediabetes syndrome: Only two studies have an estimate of prediabetes duration: Zheng et al. found a reduced fasting “active/intact” GLP-1 in prediabetic subjects that were NGT 4 years earlier, and Faerch et al. [21] studied individuals that were NGT 5 years earlier finding no difference in fasting “total” GLP-1 but found an increased 3-hour AUC GLP-1 in i-IFG versus NGT.