Cimetidine and glucose tolerance (oral and intravenous).

In the intravenous glucose tolerance test (seven subjects) plasma glucose was not modified, but the insulin levels were lower 2 min after cimetidine was given. Cimetidine modified the oral glucose tolerance test in 13 subjects by increasing the glucose values after 60 min. Insulin levels at that time were also significantly higher. These findings support the hypothesis that cimetidine, an H2 antagonist, could alter glucose handling through its effect on histaminic fibers of the islets of Langerhans.