Short-term effects of wheat bran supplementation on glucose and lipid metabolism in man

GIP concentrations similar to the maximum values observed in actively feeding ob/ob mice (Flatt et al., 1983~). Plasma GIP concentrations declined quickly indicating a relatively short half-life of the hormone in ob/ob mice. Fig. 1 b shows the plasma insulin responses to endogenous GIP released by oral administration of fat. A substantial increase in plasma GIP concentrations was achieved similar to values in fed ob/ob mice. In mice treated with saline at 30min, basal plasma glucose concentrations (not illustrated) were maintained within the range 7-l0mmol/l throughout. In these mice there was only a very small increase in plasma insulin concentrations. However, mice receiving an intraperitoneal injection of glucose at 30min showed a rise in plasma glucose concentrations exceeding 30mmol/l. These mice exhibited a marked insulin response, which was much greater than the response to glucose alone (Flatt & Bailey, 19816). The results demonstrate an insulinotropic effect of both exogenous and endogenous GIP at physiological concentrations in oblob mice. This effect is dependent on raised plasma glucose concentrations. Thus it is envisaged that elevated plasma GIP concentrations in the presence of postprandial hyperglycaemia make an important contribution to the hyperinsulinaemia of ob/ob mice.