Abstract: Objective To study the effect of change in blood sugar on renal injury caused by contrast medium in elderly patients with coronary heart disease accompanying diabetes mellitus and the corresponding preventive measures for such patients. Methods Effect of changes in blood sugar on renal injury caused by contrast medium in 70 elderly patients with coronary heart disease accompanying diabetes mellitus was retrospectively analyzed before and after angiography.Its relation with blood creatinine and eGFR levels was compared. Results The incidence of renal injury in our patients was 8.5%.The incidence of diabetes mellitus was 1% and the incidence of renal injury was 15.6% in those with diabetes mellitus accompanying renal insufficiency.The Scr level was higher 48h after operation than before operation.Renal injury occurred in 37.5% of patients with acute blood sugar increased but not in those with normal blood sugar.The prandial glucose,creatinine and eGFR levels were significantly higher in patients with coronary heart disease accompanying diabetes mellitus 24 and 48h after operation than before operation. Conclusion Effective nursing of elderly patients with coronary heart disease accompanying diabetes mellitus in perioperative period can decrease the incidence of renal injury caused by contrast medium.