This occurs because of changes in sugar levels and how sugar is handled in the kidneys, which control the amount of sugar in your system. If excess sugar is present, you will lose it through the urine. Sugar in the urine is called glucosuria. It is common during pregnancy, particularly in the second and third trimesters. Many doctors test every pregnant woman for diabetes, usually around the end of the second trimester.
Testing is particularly important if there is a family history of diabetes.
In the morning, before eating anything, you go to the lab and have the blood test done. A normal result indicates that diabetes is unlikely. An abnormal result is a high level of sugar in the blood, which needs further study. Further study involves taking the glucose-tolerance test. You have to fast the night before this test.