GCG and primary hyperparathyroidism: Also, a study of a small sample size (N = 14 subjects with asymptomatic primary hyperparathyroidism and normal glucose profile at baseline, mean age of 52.93 years) showed that glucagon-like peptide-1 (GLP-1) had a significant increase during the 75 g oral glucose test (p = 0.02 after 1 h, and p = 0.03 after 2 h versus baseline), probably a reflection of an early recovery phase of the glucose profile following parathyroidectomy [160].