Some studies have looked at more controversial potential risk factors, such as short stature.About 40–60% of women with GDM have no demonstrable risk factor; for this reason many advocate to screen all women. Typically, women with GDM exhibit no symptoms (another reason for universal screening), but some women may demonstrate increased thirst, increased urination, fatigue, nausea and vomiting, bladder infection, yeast infections and blurred vision. Pathophysiology
The precise mechanisms underlying gestational diabetes remain unknown. The hallmark of GDM is increased insulin resistance. Pregnancy hormones and other factors are thought to interfere with the action of insulin as it binds to the insulin receptor. The interference probably occurs at the level of the cell signaling pathway beyond the insulin receptor. Since insulin promotes the entry of glucose into most cells, insulin resistance prevents glucose from entering the cells properly. As a result, glucose remains in the bloodstream, where glucose levels rise. More insulin is needed to overcome this resistance; about 1.5–2.5 times more insulin is produced than in a normal pregnancy.Insulin resistance is a normal phenomenon emerging in the second trimester of pregnancy, which in cases of GDM progresses thereafter to levels seen in a non-pregnant woman with type 2 diabetes. It is thought to secure glucose supply to the growing fetus. Women with GDM have an insulin resistance that they cannot compensate for with increased production in the β-cells of the pancreas. Placental hormones, and, to a lesser extent, increased fat deposits during pregnancy, seem to mediate insulin resistance during pregnancy.
Since insulin resistance is highest in mornings, breakfast carbohydrates need to be restricted more. Ingesting more fiber in foods with whole grains, or fruit and vegetables can also reduce the risk of gestational diabetes. There is not enough evidence to indicate if one type of dietary advice is better than another.Regular moderately intense physical exercise is advised, although there is no consensus on the specific structure of exercise programs for GDM. Pregnant women who exercise have lower blood sugar levels when fasting and after meals compared to those who do not exercise. It is not clear which form of exercise is best when pregnant.Self monitoring can be accomplished using a handheld capillary glucose dosage system. Compliance with these glucometer systems can be low. There is not a lot of research into what target blood sugar levels should be for women with gestational diabetes and targets recommended to women vary around the world. Target ranges advised by the Australasian Diabetes in Pregnancy Society are as follows:
fasting capillary blood glucose levels <5.5 mmol/L
1 hour postprandial capillary blood glucose levels <8.0 mmol/L
2 hour postprandial blood glucose levels <6.7 mmol/LRegular blood samples can be used to determine HbA1c levels, which give an idea of glucose control over a longer time period.Research suggests a possible benefit of breastfeeding to reduce the risk of diabetes and related risks for both mother and child. Medication
If monitoring reveals failing control of glucose levels with these measures, or if there is evidence of complications like excessive fetal growth, treatment with insulin might be necessary.