Diarrhoea in patients with diabetes mellitus may be due to anorectal o
r rectal dysfunction that results in incontinence, intestinal secretio
n or rapid intestinal transit, or may be associated with disorders tha
t typically cause malabsorption. The latter include small bowel bacter
ial overgrowth, coeliac sprue and pancreatic insufficiency. A practica
l algorithm for diagnosis and advances in therapy is discussed.