Diabetic diarrhea

A woman with type 1 diabetes of 47 years duration has retinopathy, microalbuminuria, peripheral neuropathy, gastroparesis and coronary artery disease. Glycemic control is much improved now that she switched to continuous subcutaneous insulin infusion pump therapy. Her last HbA1c was 7.1% without hypoglycemia. Most of her complications are stable and quiescent.

However, last year she began experiencing severe explosive diarrhea. An extensive work-up including upper and lower endoscopy with biopsies, serum tissue transglutaminase IgA and IgG, assessment for fecal fat, testing for parasites and stool culture were all negative. Other than vitamin D deficiency, there was no evidence of malabsorption or other micronutrient deficiencies. She was hospitalized twice for intractable diarrhea and dehydration. Last winter, she tried to manage with scheduled-dose loperamide which resulted in severe fecal impaction and another hospitalization.

The gastrointestinal complications of diabetes are some of the most challenging to manage. Diabetic diarrhea can be difficult to distinguish from the more common irritable bowel syndrome. It can alternate with constipation or periods of normal bowel function. Diarrhea can be nocturnal and can result in incontinence of stool. The causes include autonomic neuropathy with abnormal bowel motility, small bowel bacterial overgrowth, bile acid malabsorption and anorectal dysfunction. Celiac sprue and exocrine pancreatic insufficiency are more common in type 1 diabetes and should also be ruled out.

There are several treatment options. Increasing daily fiber intake to at least 15-20 gm day can be helpful. However, fiber could result in bezoar formation in patients with constipation or gastroparesis. Bacterial overgrowth may be treated with three weeks of antibiotics such as metronidazole. Cholestyramine taken orally up to three times a day can assist with bile acid malabsorption. A gluten-free diet is essential if celiac is present. Pancreatic enzymes may be used for pancreatic exocrine dysfunction. Anti-diarrheal medication should be used with caution because it can exacerbate bacterial overgrowth and result in fecal impaction or toxic megacolon.

For patients in whom the above treatments have failed, there are few other options. Clonidine can decrease the frequency of stools but may cause hypotension. Octreotide has been used in refractory cases with mixed results. However, there is the potential for high doses of octreotide to worsen pancreatic exocrine dysfunction and malabsorption of nutrients.

Our patient was advised to minimize use of loperamide and increase fiber intake. For now, her diarrhea appears to be under control. If it returns, we will try some of the options described above.