THE EFFECT OF SHORT-TERM DIETARY SUPPLEMENTATION WITH GLUCOSE ON GASTRIC - EMPTYING OF GLUCOSE AND FRUCTOSE AND ORAL GLUCOSE-TOLERANCE IN NORMAL SUBJECTS

Recent observations indicate that gastric emptying may be influenced b y patterns of previous nutrient intake. The aims of this study were to determine the effects of a high glucose diet on gastric emptying of g lucose and fructose, and the impact of any changes in gastric emptying on plasma concentrations of glucose, insulin and gastric inhibitory p olypeptide in response to glucose and fructose loads. Gastric emptying of glucose and fructose (both 75 g dissolved in 350 mi water) were me asured in seven normal volunteers on separate days while each was on a 'standard' diet and an identical diet supplemented with 440 g/day of glucose for 4-7 days. Venous blood samples for measurement of plasma g lucose, insulin and gastric inhibitory polypeptide levels were taken i mmediately before and for 180 min after ingestion of glucose and fruct ose loads. Dietary glucose supplementation accelerated gastric emptyin g of glucose (50% emptying time 82 +/- 8 vs 106 +/- 10 min, p = 0.004) and fructose (73 +/- 9 vs 106 +/- 9 min, p = 0.001). After ingestion of glucose, plasma concentrations of insulin (p < 0.05) and gastric in hibitory polypeptide (p < 0.05) were higher during the glucose-supplem ented diet. In contrast, plasma glucose concentrations at 60 min and 7 5 min were lower (p < 0.05) on the glucose-supplemented diet. We concl ude that short-term supplementation of the diet with glucose accelerat es gastric emptying of glucose and fructose, presumably as a result of reduced feedback inhibition of gastric emptying from small intestinal luminal receptors. More rapid gastric emptying of glucose has a signi ficant impact on glucose tolerance.