This study investigated the effects of acutehyperglycemia on conscious rectal perception in responseto two different rectal distension paradigms. Elevenhealthy males were studied in random order on two separate days during euglycemia andhyperglycemia with blood glucose concentrations clampedto 3.8 ± 0.6 and 14.8 ± 0.86 mmol/liter,respectively. In order to evoke sensory responses, rapidphasic and ramplike distensions were applied to anintrarectal balloon. Rectal sensation thresholds forinitial sensation, sensation of stool and discomfort,and sensory intensities were recorded. Additionally,anorectal motor responses were investigated during phasicdistension. Acute hyperglycemia did not modify rectalsensory pressure thresholds and perception scores inresponse to phasic distension. Neither did hyperglycemia alter the resting anal sphincter pressure, thepressure threshold for eliciting the rectoanalinhibitory reflex, or the maximal anal squeeze pressure.In contrast, hyperglycemia attenuated rectal perception in response to ramplike distension. Thepressure thresholds, 10.0 ± 1.8 and 17.0 ±3.6 mm Hg for initial sensation and discomfort,respectively, during hyperglycemia were significantlyhigher than the corresponding thresholds of 4.4 ± 1.4and 11.4 ± 1.9 mm Hg observed during euglycemia(P < 0.01).="" higher="" rectal="" pressures="" were="" observed="" atall="" intensities="" of="" sensation="" of="" stool="" and="" discomfortduring="" hyperglycemia="" than="" those="" obtained="" duringeuglycemia="" (p="">< 0.01).="" hyperglycemia="" did="" not="" alterthe="" compliance="" of="" the="" rectum.="" the="" results="" of="" this="" studydemonstrate="" that="" acute="" hyperglycemia="" attenuates="" rectal="" perception,="" and="" this="" attenuation="" depends="" uponthe="" type="" of="" distension="" employed.="" our="" findings="" alsodemonstrate="" that="" anal="" sphincter="" motor="" function="" is="" notappreciably="" modified="" by="">