A 57-year-old man is evaluated for a 6-month history of persistent diarrhea. The patient describes frequent soft to watery bowel movements that sometimes awaken him from sleep. He has had fecal incontinence on several occasions along with abdominal bloating and excessive flatulence but has had no fever, abdominal or rectal pain, tenesmus, melena, hematochezia, or weight loss. Medical history includes hypertension, peripheral vascular disease, and a 40-year history of diabetes mellitus treated with insulin. The patient has not traveled recently.
Temperature is 36.9 C (98.4 F), blood pressure is 136/84 mm Hg supine and 122/77 mm Hg standing, and pulse is 72/min. The lungs are clear on auscultation and heart sounds are normal. The abdomen is nondistended, soft, and nontender with no palpable mass or hepatosplenomegaly. Bowel sounds are normal. Stool is negative for occult blood. Light touch and vibratory sensation are decreased on both feet, and bilateral ankle reflexes are absent.
Laboratory results are as follows:
Stool is negative for ova and parasites, and stool culture grows no pathogenic bacteria. Colonoscopy reveals grossly normal mucosa; random biopsies are unrevealing. Small bowel follow-through barium studies and upper gastrointestinal endoscopy with random biopsies are normal.
Which of the following is most likely contributing to this patient's condition?

Question

A 57-year-old man is evaluated for a 6-month history of persistent diarrhea.  The patient describes frequent soft to watery bowel movements that sometimes awaken him from sleep.  He has had fecal incontinence on several occasions along with abdominal bloating and excessive flatulence but has had no fever, abdominal or rectal pain, tenesmus, melena, hematochezia, or weight loss.  Medical history includes hypertension, peripheral vascular disease, and a 40-year history of diabetes mellitus treated with insulin.  The patient has not traveled recently.
Temperature is 36.9 C (98.4 F), blood pressure is 136/84 mm Hg supine and 122/77 mm Hg standing, and pulse is 72/min.  The lungs are clear on auscultation and heart sounds are normal.  The abdomen is nondistended, soft, and nontender with no palpable mass or hepatosplenomegaly.  Bowel sounds are normal.  Stool is negative for occult blood.  Light touch and vibratory sensation are decreased on both feet, and bilateral ankle reflexes are absent.
Laboratory results are as follows:
 Stool is negative for ova and parasites, and stool culture grows no pathogenic bacteria.  Colonoscopy reveals grossly normal mucosa; random biopsies are unrevealing.  Small bowel follow-through barium studies and upper gastrointestinal endoscopy with random biopsies are normal.
Which of the following is most likely contributing to this patient's condition?

Quizplus · Accepted Answer

11ec193a_97f8_6afa_853d_a58e93767fff_MD0002_00 This patient has symptoms consistent with diabetic diarrhea; a painless, watery diarrhea that can occur at night and is often associated with fecal incontinence. Patients may have periods of normal bowel movements and/or constipation. The etiology is likely multifactorial but is thought to be largely due to autonomic neuropathy leading to small bowel and colonic hypomotility, increased intestinal fluid secretion, and anorectal dysfunction. Diabetic diarrhea is a diagnosis of exclusion; workup includes stool studies, serum chemistries and endocrine studies, and endoscopic biopsy. Small intestinal bacterial overgrowth (SIBO) commonly contributes to diabetic diarrhea as gastrointestinal hypomotility allows for excessive colonization. This leads to abdominal discomfort, bloating, and flatulence; severe disease can cause malabsorption with steatorrhea and vitamin deficiency. Patients with bacterial overgrowth often have secondary lactose intolerance as well. The diagnosis of SIBO can be confirmed with a carbohydrate breath test and treated with antibiotics (eg, rifaximin); endoscopic and histopathologic studies are often nonrevealing. Patients with diabetic diarrhea in the absence of SIBO are often treated with antimotility agents (eg, loperamide). (Choices B and D) Celiac disease is common in diabetic patients due to the similar genetic predisposition. Microscopic colitis may also occur with increased frequency in patients with diabetes. Both diseases cause diarrhea; however, this patient's normal small bowel biopsy essentially rules out these disorders. (Choice C) Irritable bowel syndrome (IBS) can present with alternating diarrhea and constipation. However, the presence of nocturnal diarrhea suggests an organic cause rather than IBS. (Choice E) Pancreatic insufficiency is a rare cause of diarrhea/malabsorption in the diabetic population. It leads to steatorrhea but not watery stools. Educational objective: Autonomic dysfunction in longstanding diabetes mellitus can lead to gastrointestinal dysmotility. Diabetic diarrhea is characterized by painless, watery diarrhea, fecal incontinence, and/or alternating normal bowel movements and constipation. Small intestinal bacterial overgrowth is a common complication and may contribute to symptoms. __________ References: Diabetic diarrhea. (http://www.ncbi.nlm.nih.gov/pubmed/19765362)

A 57-Year-Old Man Is Evaluated for a 6-Month History of Persistent