The α₂-adrenoceptor agonist xylazine as an anesthetic has been widely used either alone or in combination with other anesthetics, such as ketamine, in veterinary clinic and research. In the last decade xylazine has been used in drug abusers in certain geographic area. This study investigated the effects of xylazine on blood glucose level and insulin secretion in normoglycemic and insulin-dependent diabetic monkeys.

Both adult cynomolgus (n = 10) and rhesus (n = 8) monkeys with either sex were used in the study. Xylazine (1–2 mg/kg) was administrated intramuscularly. Blood glucose, insulin, glucagon and glucagon-like peptide 1 in overnight-fasted monkeys were measured immediately before and after xylazine administration. The hyperinsulinemic-euglycemic clamp method was used in the study for assessing the potential mechanism of xylazine-induced hyperglycemia.

Xylazine administration increased the blood glucose levels from 58 ± 3 to 108 ± 12 mg/dL in normoglycemic (n = 5, p < 0.01) and from 158 ± 9 to 221 ± 13 mg/dL in insulin-dependent diabetic (n = 5, p < 0.01) monkeys and was not accompanied by any significant changes in blood insulin, glucagon, and glucagon-like peptide-1. Xylazine-induced hyperglycemia occurred within 10 min and reached the peak at 35 min after injection. Xylazine-induced hyperglycemia declined slowly in diabetic animals. The α₂-adrenoceptor antagonist yohimbine was administrated to bring down the elevated glucose level to the pre-xylazine one in 4 out of 5 diabetic animals. To assess the potential mechanism, the hyperinsulinemic-euglycemic clamp was used to maintain a nearly saturated and constant insulin level for minimizing endogenous insulin glucoregulation. Xylazine administration decreased glucose infusion rate, from 14.3 ± 1.4 to 8.3 ± 0.8 mg/min/kg (n = 6, p < 0.01) in normoglycemic rhesus monkeys, which indicates that the glucose metabolic rate (M rate) was decreased by xylazine. In addition, after clamping blood glucose level in a range of 55 to 75 mg/dL for 40 min with constant glucose infusion, xylazine administration still increased blood glucose concentration.

We conclude that xylazine administration induces hyperglycemia in normoglycemic and insulin-dependent diabetic monkeys potentially via stimulation of α₂-adrenoceptors and then reducing tissue sensitivity to insulin and glucose uptake.