2 Chronic pancreatitis and diabetes

Abstract

Chronic pancreatitis is defined by a persistent destruction of the pancreatic parenchyma replaced by fibrosis. The lesions generally start in the exocrine gland, islets being attacked later in the fibrosis. The two most frequent forms are: 1. Chronic calcifying pancreatitis which is a pancreatic lithiasis responsible for more than 95% of chronic pancreatitis. In its most frequent form, calculi are built up of more than 98% calcium salts together with fibres of a degraded residue of lithostathine, a secretory protein. This disease is related (i) in most countries to alcohol, protein, fat and tobacco and (ii) in certain tropical countries to malnutrition (low-fat, low-protein diet) for some generations. A causative role for cassava and kwashiorkor is improbable. The mechanism of calcium precipitation is partly explained by the calcium-saturation of pancreatic juice and the decreased biosynthesis of lithostathine S, the secretory protein preventing crystallization. As a rule, diabetes (and steatorrhoea) appear after a clinical evolution characterized by recurrent attacks of upper abdominal pain, generally lasting some days with transiently increased concentrations of pancreatic enzymes in serum. When diabetes appears, pain frequently disappears. Complications are mostly observed in the first 10 years of clinical evolution. 2. Obstructive pancreatitis is due to an obstacle (tumours, scars) in the pancreatic duct. It is rarely a cause of diabetes. Diabetes due to chronic pancreatitis is characterized by the low incidence of ketosis and the high incidence of insulin-induced hypoglycaemia. Patients are generally thin. Serum insulin levels, either basal or stimulated, are decreased. Glucagon is less affected. Angiopathies and retinopathies are less frequent than in non-insulin-dependent diabetes. Neural complications are fairly frequent. The diagnosis is generally easy because diabetes appears at a late stage of the disease. The treatment generally requires insulin.