Prevalence of diabetes mellitus secondary to pancreatic diseases (type 3c)

BACKGROUND: Diabetes mellitus secondary to pancreatic diseases is a condition seldom thought of in clinical practice. Yet, a high percentage of exocrine pancreatic insufficiency has been reported for the general population and especially for diabetic subjects. Thus, we investigated the prevalence of diabetes mellitus due to pancreatic diseases. METHODS: In this study, we investigated 1868 patients diagnosed with diabetes mellitus who had been admitted to our hospital during the last 24 months. Patient data were diligently studied, and patients were reclassified according to the diabetes classification as proposed by the American Diabetes Association. RESULTS: Among 1868 subjects, 172 patients could be classified as type 3c diabetes mellitus (9.2%). Among these were 135 diagnosed with chronic pancreatitis (78.5%), 12 with hereditary haemochromatosis, 14 with pancreatic cancer and 7 with cystic fibrosis. Thus, diabetes mellitus due to chronic pancreatitis occurred in this collective in 7.2% of all diabetic subjects. Misclassification of these patients was very common. Only 51.2% (88/172) were initially classified correctly. Most type 3 diabetes patients were initially misclassified as type 2 diabetes (69/84). CONCLUSIONS: Diabetes mellitus secondary to pancreatic diseases (especially chronic pancreatitis) seems more common than generally believed with a prevalence of 9.2% among the subjects studied here. Because the awareness of this diabetes type is poor, misclassification is quite frequent. A common problem seems to be the differentiation between type 2 and type 3. Yet, the right classification of diabetes mellitus is important, because there are special therapeutic options and problems in patients with diabetes secondary to pancreatic diseases.