Effects of gatifloxacin on serum glucose concentration in normal and diabetic rats.

To clarify the mechanisms of gatifloxacin (GFLX)-induced hypoglycemia and hyperglycemia, the effect of GFLX on serum glucose levels was investigated in normal and diabetic rats. Rats received an intravenous injection of GFLX and their arterial blood was sampled periodically. Diabetic rats were produced by the intraperitoneal injection of streptozotocin and nicotinamide. In normal rats, the serum glucose concentration was decreased by GFLX at 25 and 50 mg/kg, while it was elevated 0.25 h after the injection of 100 mg/kg of GFLX. Serum immunoreactive insulin (IRI) levels increased as the dose of GFLX increased. The serum epinephrine concentration rose rapidly after the injection of GFLX at 50 and 100 mg/kg. In diabetic rats, the serum glucose concentration was actually increased by GFLX at 50 mg/kg. The baseline concentration of IRI was lower and the degree of the elevation caused by GFLX was smaller in diabetic rats. Both diabetic and control rats showed an increase in the serum epinephrine concentration after the injection of 50 mg/kg of GFLX. In conclusion, GFLX-induced secretion of insulin and epinephrine would contribute to the abnormalities in glucose homeostasis. The response of serum glucose to GFLX may differ between diabetic and normal rats due to the alteration of insulin secretion.