Acute hyperglycaemia aVects anorectal motor and sensory function in normal subjects

Background—The pathogenesis of ano-rectal dysfunction, which occurs fre-quently in patients with diabetes mellitus, is poorly defined. Recent studies indicate that changes in the blood glucose concen-tration have a major reversible eVect on gastrointestinal motor function. Aims—To determine the eVects of physi-ological changes in blood glucose and hyperglycaemia on anorectal motor and sensory function in normal subjects. Subjects—In eight normal subjects meas-urements of anorectal motility and sensa-tion were performed on separate days while blood glucose concentrations were stabilised at 4, 8, and 12 mmol/l. Methods—Anorectal motor and sensory function was measured using a sleeve/ sidehole catheter incorporating a balloon, and electromyography. Results—The number of spontaneous anal relaxations was greater at 12 mmol/l than at 8 and 4 mmol/l glucose (p<0.05 for both). Anal squeeze pressures were less at a blood glucose of 12 mmol/l when com-pared with 8 and 4 mmol/l (p<0.05 for both). During rectal distension, residual anal pressures were not significantly dif-ferent between the three blood glucose concentrations. Rectal compliance was greater (p<0.05) at a blood glucose of 12 mmol/l when compared with 4 mmol/l. The threshold volume for initial percep-tion of rectal distension was less at 12 mmol/l when compared with 4 mmol/l (40 (20–100) ml versus 10 (10–150) ml, p<0.05). Conclusions—An acute elevation of blood glucose to 12 mmol/l inhibits internal and external anal sphincter function and in-creases rectal sensitivity in normal sub-jects. In contrast, physiological changes in blood glucose do not have a significant eVect on anorectal motor and sensory function