Candesartan (8 mg/d) was administered for 2 weeks to eight patients with essential hypertension to investigate the effect of an angiotensin II receptor antagonist on insulin sensitivity. The effect of candesartan on sodium-retaining action and the activation of pressor systems by hyperinsulinaemia, which might be related to pressor mechanisms in essential hypertension, was also investigated in this study. In patients with essential hypertension, candesartan restored insulin sensitivity to the level of that in normotensive subjects. Candesartan treatment attenuated the sodium-retaining action of hyperinsulinaemia. These findings suggest that inhibition of angiotensin II action by candesartan can improve insulin sensitivity and inhibit the sodium-retaining action associated with hyperinsulinaemia in essential hypertension.