Digestive, Anorectal, and Urogenital Functions in Patients with Type 2 Diabetes Mellitus, Impaired Glucose Tolerance and Normal Glucose Tolerance: Association with Autonomic Neuropathy

Aims Gastrointestinal disorders, including constipation and fecal incontinence, are common in type 2 diabetes mellitus (T2DM) and may derive from diabetic autonomic neuropathy, severe intestinal bacterial overgrowth, or a dysfunctional anorectal sphincter. The present study aims to characterize the correlation between these conditions. Methods Patients with T2DM, prediabetes, and normal glucose tolerance (NGT) were included. The anorectal function was assessed with high-resolution anorectal manometry. Patients were screened for autonomic neuropathy by measuring olfactory, sweat, and erectile dysfunction as well as heart rate variability. Constipation and fecal (in-)continence were evaluated using validated questionnaires. Breath tests were used to assess severe intestinal bacterial overgrowth. Results We included 59 participants (32 (54.2 %) with T2DM, 9 (15.3 %) with prediabetes, and 18 (30.5 %) NGT). The presence of autonomic neuropathy, severe bacterial overgrowth, and symptoms of constipation and incontinence were comparable. HbA1c was correlated with an increased anorectal resting sphincter pressure (r = 0.31, P = 0.019) and constipation symptoms (r = 0.30, P = 0.031). In patients with a long-standing diagnosis of T2DM, significantly higher values for maximum anorectal resting pressure (Delta = + 27.81 +/- 7.84 mmHg, P = 0.0015) and baseline pressure (Delta = 20.50 +/- 9.74 mmHg, P = 0.046) were found compared with NGT, but not with prediabetes. Conclusions Long-standing T2DM increases anorectal sphincter activity, and constipation symptoms are associated with higher HbA1c levels. The lack of an association of symptoms with autonomic neuropathy suggests glucotoxicity as the primary mechanism.