Cephalic phase of insulin secretion: our normal state is fasting

"In human subjects, as well as in animals (Naim, Kare, & Merrie, 1978), taste stimuli can elicit insulin secretion by the beta cells of the pancreas (Bellisle, Louis-Sylvestre, Demozay, Blazy, & Le Magnen, 1983; Berthoud, Trimble, Siegel, Bereiter, & Jeanrenaud, 1980). The early increase of insulin secretion following gustatory stimulation (within 4 min) is of cephalic origin. The specific characteristic of this phenomenon (CPIR, cephalic phase insulin release) is the plasma insulin increase prior to the rise of blood glucose. Typically, plasma insulin concentrations increase within 2 min after oral stimulation, reach their maximum at 4 min and return to baseline within 10 min (Teff & Engelman, 1996; Teff, Mattes, & Engelman, 1991; Teff, Mattes, Engelman, & Mattern, 1993). It could be shown that the meal composition has no effect on the type of the early insulin response although three different types of responses have been observed: high and moderate increase or decrease of plasma insulin (Bellisle et al., 1983). Negative responses have been interpreted as the descending phase of spontaneous oscillations of insulinemia. This effect has been described in both animals and humans."

http://www.sciencedirect.com/science/article/pii/S019566630800411X