Disturbances in anorectal function in patients with diabetes mellitus and faecal incontinence

The pathophysiology of faecal incontinence in diabetes mellitus is poorly understood. The study was designed to document the anorectal dysfunctions in diabetic patients with faecal incontinence.

Multiport anorectal manometry and electromyography were done in 11 diabetic patients with faecal incontinence and in 20 healthy controls.

Basal and squeeze pressures were reduced (P < 0.05) in the diabetic patients compared with the control subjects. During basal recording six patients showed regular oscillations in anal electrical activity and pressure with an amplitude of 10-40 (median: 25) cmH2O and a frequency of 6-10 (median: 8) min-1. Nine patients also exhibited spontaneous transient anal relaxations with an amplitude of 15-50 (median: 40) cmH2O and a duration of 15-720 (median: 60)s, and in six of them leakage occurred as the anal pressure fell below the rectal pressure. None of the control subjects showed oscillation or spontaneous relaxations. In patients there was a greater tendency for repetitive rectal contractions in response to rectal distension and reduced rectal compliance (P < 0.01). During rectal distension four patients showed no anal relaxation, and in the remainder relaxation occurred at an abnormally high threshold. However, the residual pressures were lower (P < 0.05) than in control subjects and often fell below rectal pressure, whereupon leakage occurred. There was no significant difference in the distension thresholds for rectal sensation between patients and control subjects, but in 9/11 patients the perception of rectal sensation was delayed by more than 2s (P < 0.05).

These results indicate that aetiology of faecal incontinence in diabetic patients is multifactorial and, suggest for the first time, that instability of the internal sphincter probably plays a major role.