To assess a possible influence of short-term administration of somatostatin on remission development in adult patients with newly diagnosed diabetes mellitus type 1, the somatostatin analog octreotide was given for two weeks after the establishment of the diagnosis at the daily dose of 150 microg subcutaneously in addition to the regular insulin and metabolic therapy. When compared to the control group, the remission was achieved earlier in the octreotide group (6+/-4 weeks vs. 11+/-12 weeks in the control group, p 0.05) and its duration was longer (99+/-49 weeks vs. 49+/-31 weeks in the control group, p 0.05). Moreover, remission also appeared in patients from the octreotide group with lower endogenous residual secretion of insulin (basal C peptide at the time of diagnosis in patients who later entered remission was 0.23+/-0.16 nmol/l vs. 0.34+/-.18 nmol/l in the control group, p<0.05). The increase of 24-h urine excretion of C-peptide after the therapy with octreotide was predictive for remission development. It can thus be concluded that octreotide administration in adults with newly diagnosed diabetes mellitus type 1 positively influences both the onset and duration of remission.