Causes of Gestational Diabetes
Scientists believe gestational diabetes is caused by the hormonal changes and metabolic demands of pregnancy together with genetic and environmental factors.
Insulin Resistance and Beta Cell Dysfunction
Hormones produced by the placenta and other pregnancy-related factors contribute to insulin resistance, which occurs in all women during late pregnancy. Insulin resistance increases the amount of insulin needed to control blood glucose levels. If the pancreas can't produce enough insulin due to beta cell dysfunction, gestational diabetes occurs.
As with type 2 diabetes, excess weight is linked to gestational diabetes. Overweight or obese women are at particularly high risk for gestational diabetes because they start pregnancy with a higher need for insulin due to insulin resistance. Excessive weight gain during pregnancy may also increase risk.
Having a family history of diabetes is also a risk factor for gestational diabetes, suggesting that genes play a role in its development. Genetics may also explain why the disorder occurs more frequently in African Americans, American Indians, and Hispanics/Latinos. Many gene variants or combinations of variants may increase a woman's risk for developing gestational diabetes. Studies have found several gene variants associated with gestational diabetes, but these variants account for only a small fraction of women with gestational diabetes.
Future Risk of Type 2 Diabetes
Because a woman's hormones usually return to normal levels soon after giving birth, gestational diabetes disappears in most women after delivery. However, women who had gestational diabetes are likely to develop it with later pregnancies and have a 35-60% chance of developing type 2 diabetes 10-20 years after delivery. Women with gestational diabetes should be tested for persistent diabetes 6-12 weeks after delivery and at least every 3-years thereafter.
Also, exposure to high glucose levels during gestation increases a child's risk for becoming overweight or obese and for developing type 2 diabetes later on. The result may be a cycle of diabetes affecting multiple generations in a family. For both mother and child, maintaining a healthy body weight and being physically active may help prevent type 2 diabetes.