High blood glucose after six months of pregnancy may be caused by hormone blocking insulin secretion, irrational diet and family history of diabetes. 1. Hormonal obstruction of insulin secretion: During pregnancy, the placenta of pregnant women may secrete hormones that block insulin, which will lead to a decrease in insulin secretion, thus easily causing high blood sugar. 2. Irrational diet: It may be due to overeating during pregnancy, like to eat high sugar foods and carbohydrates, etc., in the long run, can cause high blood sugar phenomenon. 3. Family history of diabetes: for pregnant women with a family history of diabetes, pregnant women without a family history of diabetes are more likely to develop diabetes, which can also appear high blood sugar. Six months pregnant with high blood sugar may also be caused by other reasons, it is recommended that pregnant women go to the hospital in a timely manner, in accordance with the doctor’s instructions for treatment, to avoid delaying the condition.