Effects of orally administered prednisone on glucose tolerance and insulin secretion in clinically normal dogs.

Prednisone was administered orally for 4 weeks at a dosage of 1.1 mg/kg of body weight/d, in divided dose every 12 hours, to a group of healthy adult dogs (n = 12). Intravenous glucose tolerance testing was performed before and after the 28-day regimen in each dog, as well as in dogs of a control group (n = 6). Glucose metabolism was evaluated by measurement of preprandial plasma insulin and glucose concentrations, total insulin secretion, and fractional clearance of glucose. Mean preprandial plasma insulin and glucose concentrations were not increased after the 4-week regimen of prednisone. Total insulin secretion in response to an IV administered glucose load was not increased in treated dogs, compared with pretreatment values or with values for control dogs. The fractional clearance of glucose was also not altered in dogs given prednisone. Results indicate that anti-inflammatory doses of prednisone, given orally for 4 weeks, probably do not alter insulin sensitivity or glucose tolerance in clinically normal dogs.