Serum trypsin concentration and pancreatic trypsin secretion in insulin-dependent diabetes mellitus

Fasting serum trypsin concentration and pancreatic trypsin output, stimulated by secretin and cholecystokinin-pancreozymin, were measured in 18 patients with insulin-dependent diabetes, to assess a possible correlation between these two indices of exocrine pancreatic function. Serum trypsin concentration was subnormal in 13, and pancreatic trypsin output was decreased in 14 patients, but there was no significant correlation between the two measurements. There was no correlation between serum trypsin and residual beta cell function measured by plasma C-peptide immunoreactivity (CPR). After an interval of four years serum trypsin measurements were repeated in 11 subjects. All individual trypsin levels were lower than the previous results, the difference being highly significant (t = 9.0; p < 0.001). Serum trypsin concentration therefore represents a qualitative index of reduced exocrine pancreatic function in diabetes, but has no value in quantitating the degree of deficiency.