Serum isoamylase activities in diabetes mellitus.

Serum pancreatic isoamylase activities were used to assess exocrine pancreatic function in 39 patients with diabetes mellitus (21 on insulin, 12 on sulphonylureas, and six on biguanides or diet), and the results were compared with serum immunoreactive trypsin concentrations. Thirteen patients had decreased pancreatic isoamylase activity, the insulin-dependent diabetics showing the highest incidence of abnormality. This incidence of abnormality is similar to that previously described for serum immunoreactive trypsin, and the two procedures gave excellent overall correlation (r = 0.9). Our observations offer further evidence that pancreatic exocrine function is impaired in diabetes mellitus. Serum isoamylase determination provides a convenient, inexpensive, and rapid procedure for its detection.