Like type 1 and type 2 diabetes mellitus, gestational diabetes affects how the cells use glucose. Glucose is the cells’ main source of energy. Unlike other types of diabetes, this type only develops during pregnancy. (1)
Gestational diabetes usually develops during the last half of pregnancy. It can sometimes present as early as the 20th week of gestation, (1) but is generally diagnosed between the 24th and 28th week.
It is an early warning for the risk of developing type 2 diabetes. (3) An estimated 18 percent of all pregnant women in the United States are diagnosed with gestational diabetes. (4)
Researchers do not know exactly why some women develop this condition. It is known that during pregnancy, the placenta, which is the organ that connects the baby by the umbilical cord to the uterus, produces certain hormones. These hormones help the baby develop.(4)
But, they also interfere and block insulin’s ability to manage glucose. (2). The resulting condition is called insulin resistance.
As the baby grows, the placenta produces increased amounts of the insulin-blocking hormones. (1) As insulin resistance increases, the mother’s pancreas produces more insulin, about three times the normal amount.
However, when the pancreas is unable to produce enough insulin to overcome the effect of the increased hormones, glucose remains in the blood rather than entering the cells. Blood glucose levels rise resulting in gestational diabetes. (2)
A woman is at risk if her pre-pregnancy weight is 20 percent or more over her ideal body weight. A family history of a parent or sibling having diabetes is a risk factor. Pregnant woman over the age of 25 are more likely to develop gestational diabetes.
Having gestational diabetes with a previous pregnancy or previously giving birth to a baby weighing over nine pounds or having a stillbirth increases the chances of developing insulin resistance during pregnancy. (2)
Most healthcare practitioners routinely recommend a glucose screening test called a glucose challenge test or GCT between the 24th and 28th week of pregnancy.