A comparison of insulin suppression tests performed with somatostatin and octreotide with particular reference to tolerability

To evaluate the tolerability of insulin suppression test (IST) using octreo tide instead of somatostatin. we compared the steady-state plasma glucose ( SSPG) values and the safety during and after the test in 17 normal voluntee rs. The subject received IST twice (with somatostatin or with octreotide) i n random order. During the test, all subjects were infused with regular ins ulin and glucose simultaneously for 180 min. In addition, either somatostat in or octreotide was infused intravenously over the same period of time. Pl asma glucose, insulin and C-peptide were measured. The subject response to the test was recorded during and one day after the test by a structured que stionnaire. The SSPG and the steady-state plasma insulin (SSPI) values reac hed during IST were similar, irrespective of the use of somatostatin or oct reotide. There was a positive correlation between the SSPG values obtained from both methods (r = 0.67, P = 0.003). However, the mean intra-individual coefficient of variation is 17.9% for SSPG. The SSPG levels, no matter fro m which method, correlated positively with the 2-h insulin after oral gluco se challenge. Most adverse events (especially gastrointestinal discomfort) occurred after the test, and increased much more after using octreotide tha n somatostatin (P = 0.002 by chi (2) test). In conclusion, the SSPG values measured by IST using octreotide or somatostatin are similar in normal heal thy subjects. Yet, the octreotide method has mon adverse events after the t est. (C) 2001 Elsevier Science ireland Ltd. All rights reserved.