The general rule is to have a glucose tolerance test between 24 and 28 weeks of pregnancy. The glucose tolerance requires a fasting blood draw to check fasting blood sugar, and then drinking sugar water, which is made with 75g of glucose in 300mL of water, and drinking it within five minutes. From the time of the first sip of sugar water, blood is drawn every hour for 1-2 hours after drinking the sugar water, and then the three blood glucose values are compared with the diagnostic criteria for gestational diabetes in obstetrics, and gestational diabetes is diagnosed if any of them is high. If the diagnosis of gestational diabetes is made, medical nutrition therapy will be administered as diabetes. Medical nutrition therapy requires dietary management plus exercise therapy, along with monitoring of blood glucose. If blood glucose is still higher than normal, insulin will need to be added.