IS THE EFFECT OF ACUTE HYPERGLYCEMIA ON INTERDIGESTIVE ANTRODUODENAL MOTILITY AND SMALL-BOWEL TRANSIT MEDIATED BY INSULIN

Acute hyperglycaemia inhibits antroduodenal motility. In non-diabetic subjects this inhibitory effect may result from reactive endogenous hy perinsulinaemia. Therefore, we investigated the effects of hyperinsuli naemia during both hyperglycaemia and euglycaemia on interdigestive an troduodenal motility (perfusion manometry) and duodenocaecal transit t ime (DCTT; lactulose breath-Hz test). Six healthy volunteers (age 20-2 6 years) were studied for 240 min on three separate occasions in rando m order during: (a) i.v. saline (control); Cb) acute hyperglycaemic hy perinsulinaemia (HG) with plasma glucose at 15 mmol L-1 and (c) euglyc aemic hyperinsulinaemia (HI) with plasma insulin at 80 mU L-1 and gluc ose at 4-5 mmol L-1. Results: DCTT was significantly (P<0.05) prolonge d during HG (158 +/- 23 min) compared with control (95 +/- 25 min), wh ereas HI had no effect (100 +/- 17 min). Mean duration of complete mig rating motor complex (MMC) cycles was significantly (P<0.05) reduced d uring HG (63 +/- 9 min) compared with control (103 +/- 15 min) and HI (105 +/- 16 min), which resulted from a significantly (P<0.05) shorter duration of phase II. Antral motility was significantly (P<0.05) redu ced during both HI (20 +/- 8 contractions 240 min(-1)) and HG (9 +/- 5 ) compared with control (43 +/- 7). It is concluded that in healthy su bjects hyperglycaemia prolongs DCTT, increases duodenal MMC cycle freq uency and inhibits antral motility. Hyperinsulinaemia reduces antral m otor activity but has no effect on interdigestive duodenal motility or DCTT. Thus, other factors, apart from insulin, mediate the inhibitory effect of hyperglycaemia on interdigestive intestinal motility and tr ansit.