Hyperglycaemic effect of xylazine

In cats, xylazine, an analogue of clonidine, produced hyperglycaemia when injected intravenously. The effect was obtained in unanaesthetized cats and in pentobarbitone sodium anaesthesia. The hyperglycaemia was not a central effect, nor due to adrenaline release from the adrenals, nor to a direct action of xylazine on the liver. It resulted from a fall in plasma insulin produced by an action of xylazine on the pancreas, inhibiting insulin secretion without affecting glucagon secretion. The increase in the glucagon/insulin ratio, by stimulating glucose production in the liver, was probably responsible for the xylazine-induced hyperglycaemia.