Pathogenesis of Fecal Incontinence in Diabetes Mellitus: Evidence for Internal-Anal-Sphincter Dysfunction

We studied 16 patients with diabetes and fecal incontinence. The onset of incontinence coincided with the onset of chronic diarrhea in most patients. Episodes of incontinence occurred when stools were frequent and loose; however, 24-hour stool weights were usually within normal limits. All patients had evidence of autonomic neuropathy, and one third had steatorrhea. Incontinent diabetics had a lower mean basal anal-sphincter pressure than 35 normal subjects (63±4 vs. 37±4 mm Hg; P<0.001), reflecting abnormal internalanal-sphincter function. The increment in sphincter pressure with voluntary contraction (external-sphincter function) was not significantly different from normal. Incontinent diabetics also had impaired continence for a solid sphere and for rectally infused saline. In contrast, 14 diabetics without diarrhea or incontinence had normal sphincter pressures and normal results on tests of continence, even though 79 per cent had evidence of autonomie neuropathy and nearly half had steatorrhea. We conclude that incontinence in diabetic patients is related to abnormal internal-anal-sphincter function, and that as a group, diabetics without diarrhea do not have latent defects In continence. (N Engl J Med. 1982; 307: 1666–71.) FECAL incontinence and diarrhea have been recognized as complications of long-standing diabetes mellitus for nearly 50 years and are thought to be particularly common when diabetes is complicated by neuropathy.^1,2 Although there have been many descriptions of diabetic diarrhea and several attempts to define its pathogenesis,^{3 4 5 6 7 8 9 10} understanding of this disorder remains incomplete. Even less is known about the pathogenesis of fecal incontinence in diabetics. Two papers incidentally reported on the dynamics of the anal sphincter in individual diabetic patients in the course of studies of fecal incontinence with a variety of causes.^11,12 In the first study,¹¹ four incontinent patients with.