A 25-year-old man comes to the physician for diarrhea for the past 5 months. He has 6-8 greasy, floating stools daily. The diarrhea is worse postprandially. There is no pain, blood, or mucous in the stool. He has type I diabetes mellitus. Vitals are normal. Laboratory studies show:
Hemoglobin 10 g/dL
MCV 72 fL
Leukocytes 7,000/μL
Platelets 300,000/μL
Which of the following is the most likely explanation for this patient’s findings?