AIM The effects of calcium antagonist diltiazem on
plasma insulin levels were investigated in rats. METHODS Plasma insulin
was measured with radioimmunoassay method. RESULTS In the fasting rat,
plasma insulin levels were significantly increased after ig
diltiazem 10 mg·kg -1 and 100 mg·kg -1 , and the level of plasma insulin was increased by 131% 30 min after administration of diltiazem 100 mg·kg -1 in comparison with that of control group. Diltiazem increased the plasma insulin level markedly in glucose tolerance test of the rat. In the hyperglycemia rat induced by adrenaline, diltiazem 100 mg·kg -1 weakly increased the plasma insulin level only at 1 h after administration. CONCLUSION Diltiazem increases the plasma insulin levels in the fasting rat and glucose loaded rat. The increase of plasma insulin level induced by diltiazem is due to the hyperglycemic action of diltiazem and other effect, probably a direct or an indirect insulin release action on pancreas of the rat.