Diabetic patients with diarrhea may present clinical challenges in diagnosis and treatment. Particular diagnoses are more prevalent in diabetic patients than in the general population. Medications are often a culprit for chronic diarrhea, and the medication list should always be carefully scrutinized for those with diarrhea as a side effect. In diabetic patients, metformin is a common cause of diarrhea. Diabetic patients are more likely to have associated diseases (eg, celiac sprue and microscopic colitis) that present with diarrhea as the sole complaint. Ingested sugar-free foods that may contain sorbitol or other agents can cause diarrhea in diabetic patients. Finally, diabetic enteropathy can itself cause diarrhea. The various etiologies can be diagnosed with a thorough history and appropriate diagnostic tests. This article focuses on the etiologies of diarrhea that are seen with higher incidence in diabetic patients.