Exocrine pancreatic insufficiency in diabetic patients is frequent. Studies based on fecal elastase-1 measurement give prevalence rates of about 50 % in type 1 and 33 % in type 2 diabetic patients. Nevertheless, not all patients report typical symptoms like diarrhea, steatorrhea and weight loss. For indirect testing the determination of fecal elastase-1 has the highest sensitivity and specificity. This test should be performed at least in all symptomatic patients. For differential diagnosis celiac disease (with a prevalence of about 3-5 % of type 1 diabetic patients), autonomic neuropathy, but also diseases like irritable colon and gastrointestinal tumors have to be taken into account. Patients with symptoms and a fecal elastase-1 < 100 µg/g should be treated with pancreas enzymes in adequate daily doses administered at main meals. Treatment improves symptoms significantly, supply with fat soluble vitamins is normalised, risk for osteoporosis is reduced. An improvement of glucose metabolism is but not seen in all studies. A pancreatogenic diabetes, also termed as type 3c diabetes, has not primarily to be treated with insulin, often-at least initially-treatment with oral antidiabetic drugs is possible and sufficient.