Isosorbide nitrate tablets do not usually cause an increase in blood sugar. There are no adverse reactions found in the instructions for the drug that cause elevated blood sugar, so the drug has no effect on blood sugar. The pharmacological effect of the drug is to relax the vascular smooth muscle, it makes the myocardial oxygen consumption decrease and oxygen supply increase, thus relieving angina pectoris. So clinically the drug is used for long-term treatment of coronary heart disease; prevention of angina pectoris; treatment of persistent angina pectoris after myocardial infarction; combined with digitalis or diuretics, treatment of chronic congestive heart failure; treatment of pulmonary hypertension. Occasional adverse reactions such as headache, facial flushing, vertigo, and upright hypotension have been observed with the drug. The drug is contraindicated in shock, circulatory collapse, severe hypotension, acute myocardial infarction, hypertrophic obstructive cardiomyopathy, constrictive pericarditis or pericardial tamponade, severe anemia, glaucoma, increased intracranial pressure, primary pulmonary hypertension, and hypersensitivity to nitro compounds. Postural hypotension, increased intracranial pressure and lactating women should be cautious; the drug should not be suddenly stopped during the use of the drug to avoid causing adverse drug reactions. If the drug is needed, it should be used under the guidance of a specialist.