Evaluation of Chronic Diarrhea in Type 2 Diabetes

Initial Clinical Assessment

The American Gastroenterological Association recommends that patients with type 2 diabetes presenting with chronic diarrhea and abdominal pain should undergo targeted blood and stool testing to exclude inflammatory bowel disease, celiac disease, and medication-induced diarrhea, followed by colonoscopy with biopsies if alarm features are present or initial testing is abnormal 1, 2
Weight loss is a critical alarm feature that excludes functional disorders and necessitates colonoscopy within 2-4 weeks 3, 2
Nocturnal diarrhea suggests organic disease rather than functional bowel disorder 4, 3
Blood in stools or iron deficiency anemia requires immediate colonoscopy to exclude inflammatory bowel disease or colorectal cancer 1, 2
Family history of inflammatory bowel disease, celiac disease, or colorectal cancer increases pretest probability of organic disease 4, 6

The American Gastroenterological Association recommends ordering a complete blood count to assess for anemia, which may indicate celiac disease, inflammatory bowel disease, or malignancy 4, 2
IgA tissue transglutaminase (tTG) with total IgA level should be ordered to screen for celiac disease, which has a higher prevalence in diabetic patients and presents with chronic diarrhea 1
Fecal calprotectin or fecal lactoferrin should be obtained to distinguish inflammatory from non-inflammatory causes of diarrhea, with sensitivity >90% for inflammatory bowel disease 1, 2
Giardia antigen testing is strongly recommended, as Giardia is a common cause of chronic diarrhea with high diagnostic accuracy 1

Colonoscopy with biopsies is mandatory in the presence of any alarm features (weight loss, nocturnal symptoms, blood in stools, anemia) and should be performed within 2-4 weeks 2
Elevated fecal calprotectin (>50 mg/g) indicating inflammatory bowel disease requires colonoscopy with biopsies 7, 1
The American Gastroenterological Association suggests testing for bile acid diarrhea in patients with chronic diarrhea, though specific tests (SeHCAT) are not available in North America 1
An empiric trial of bile acid binders (cholestyramine) is reasonable if bile acid diarrhea is suspected clinically 1