In order to characterize seasonal variations of beta cell function in the edible dormouse (Glis glis), the dynamics of insulin release were examined during perfusion of the isolated pancreas. The B cells exhibited biphasic insulin secretion; however, the dynamic response differed from that of the rat in that there was a steady-state second release phase. Glucose-induced insulin release changed according to the seasons. With 16.8 mmol/l glucose, the average insulin release of the late phase was 30.8 +/- 12.6 ng/min in winter, 7.4 +/- 3.2 ng/min in spring, 13.1 +/- 3 ng/min in summer and 23.3 +/- 4.4 ng/min in autumn. The glucose-induced insulin release, expressed as percent of the insulin content of the pancreas, varied according to the season: it represented 2.23 +/- 0.31% in winter, 1.28 +/- 0.10% in spring, 1.56 +/- 0.15 in summer and 2.6 +/- 0.11 in autumn. It is suggested that in spring and summer, the edible dormouse B cell secretion mechanism is less sensitive to glucose than in the other seasons.