Twenty-four-hour variations of plasma pancreatic polypeptide, insulin and glucagon in normal human subjects

Twenty-four-hour variations of plasma hPP levels together with plasma glucose, IRI and GI levels were studied in four normal human subjects. Before examination, their food intakes were strictly controlled during two days' hospitalization. Plasma hPP values were assayed by a radioimmunoassay. They showed sharp peaks after each meal. Mean levels of hPP just prior to breakfast were 88 +/- 26 pg/ml (SEM), and the peak values of the plasma hPP one hour after each meal were 307 +/- 124 pg/ml, 398 +/- 77 pg/ml, and 544 +/- 118 pg/ml, respectively. During the nocturnal sleeping period the hPP levels were stable and returned to the fasting level of the previous morning. IRI increased significantly after each meal, but no significant change was found in plasma GI levels.