Gestational diabetes: how is this disorder diagnosed during pregnancy


Gestational diabetes can affect one in ten pregnant women. It’s a decrease of carbohydrate tolerance that is diagnosed for the first time during gestation, regardless if treatment with insulin is required or not.

The disorder is easier to control than the diabetes previous to pregnancy and it also causes less maternal complications. However, just as pregestational diabetes, can also affect the fetus.

The fetus can have high levels of insulin in blood (hyperinsulinism), exaggerated growth, lack of oxygen at the level of tissues and diverse metabolic alterations.

In order to detect this pathology, a screening test called O’Sullivan is carried out on the woman during pregnancy, consisting in determining the glycemic values (glucose in blood) one hour after ingesting 50 grams of glucose (a sugary liquid solution). A blood glucose value higher or equal to 140 mg/dl is considered a pathological result.

This test is performed already in the first-trimester if it’s a high risk pregnancy, and in the second-trimester to all pregnant women. The test is repeated in the third-trimester if there are alterations in the ultrasounds or if the pregnant woman already showed high levels of glucose in the previous test.

In the cases where the O’Sullivan test comes out altered, a second diagnostic test called oral glucose overload, OGTT or glucose curve needs to be performed. This test requires previous diet of 3 days, during which 100 grams of glucose are administrated repeatedly and 4 blood extractions are carried out. Gestational diabetes will be diagnosed if the values come out altered.

Gestational diabetes requires strict control of the diet, glycemic values and the acetone level in urine, as well as an exhaustive ultrasound follow-up to make sure that the condition is not affecting the fetus.