The tests
A glucose tolerance blood test (GTT) aims to detect diabetes caused by pregnancy, called gestational diabetes. About 2.6% of all pregnant women have diabetes (10% of which already having diabetes before the pregnancy and 90% developing it as a result of pregnancy).
Essentially, diabetes happens when sugar (or glucose) accumulates in the bloodstream, known as hyperglycaemia. The pancreas is unable to produce enough insulin to carry the glucose eaten from foods into the body's cells and muscles to be used for energy. If there is insufficient insulin, the sugar remains in the person's bloodstream, accumulating to high levels and causing the physical signs of diabetes.
Pregnancy places an added strain on the pancreas for a few women, leading to impaired glucose metabolism and a temporary diabetic condition that lasts until after the baby is born. Once the
placenta is delivered, blood sugar levels return to normal within 24 hours.
If gestational diabetes develops, it normally starts after 20 to 24 weeks of pregnancy. Women who develop gestational diabetes are generally more likely to have gestational diabetes with a subsequent pregnancy (but this is not always the case), and are at increased risk of developing diabetes later in their life.
Babies of diabetic women are not born with diabetes. However, due to a genetic inheritance, they may also be at a slightly increased risk of developing diabetes later in their life.
Most women with gestational diabetes manage their condition by changing their diet. A few women require insulin injections if their new diet is unable to keep the blood sugar levels below 8.0mmol/L. The main health risk for pregnant women with uncontrolled gestational diabetes is producing an abnormally large baby (over 4.5 kg or about 10lb), called fetal macrosomia or large for gestational age (LGA). You can read more in
large babies.
Having a larger than normal baby can increase the chances of: