Gestational diabetes is a type of diabetes that can develop during pregnancy in women who don’t already have diabetes. It occurs when the body can’t make enough insulin during pregnancy, which is a hormone made by the pancreas that acts like a key to let blood sugar into the cells in the body for use as energy. The exact cause of gestational diabetes is not known, but it is believed to be related to hormonal changes during pregnancy that can make insulin less effective, a condition referred to as insulin resistance. The placenta supplies a growing fetus with nutrients and water, and also produces a variety of hormones to maintain the pregnancy. Some of these hormones, such as estrogen, cortisol, and human placental lactogen, can have a blocking effect on insulin, which usually begins about 20 to 24 weeks into the pregnancy. As the placenta grows, more of these hormones are produced, and the risk of insulin resistance becomes greater. Normally, the pancreas is able to make additional insulin to overcome insulin resistance, but when the production of insulin is not enough to overcome the effect of the placental hormones, gestational diabetes results.

Risk factors for gestational diabetes include being overweight or obese, not being physically active, having prediabetes, having had gestational diabetes during a previous pregnancy, having polycystic ovary syndrome, and having an immediate family member with diabetes. Women who are overweight or have obesity may already have insulin resistance when they become pregnant, and gaining too much weight during pregnancy may also be a factor. Having a family history of diabetes makes it more likely that a woman will develop gestational diabetes, which suggests that genes play a role.

It is important to manage gestational diabetes to ensure a healthy pregnancy and baby. Women with gestational diabetes are at increased risk of high blood pressure during pregnancy, having a large baby that needs to be delivered by cesarean section, and having a baby with low blood sugar or developing type 2 diabetes later in life. To manage gestational diabetes, women should go to all prenatal appointments and follow their treatment plan, which may include checking blood sugar levels, eating healthy foods, exercising, and taking medication if necessary.