Blood glucose screening, also called glucose tolerance measurement, is performed in the early morning on an empty stomach after 8 hours without any caloric intake. Adults are given 75g of anhydrous glucose by mouth, dissolved in 250-300mL of water and consumed within 5-10 minutes. Plasma glucose was taken intravenously before drinking the sugar and half an hour, one hour, two hours and three hours after drinking the glucose water. Be careful not to drink tea or coffee, smoke or do strenuous exercise during the test. Three days before the glucose tolerance test, consume sufficient carbohydrates and stop taking any medications that may affect the results.