Interview has been edited for clarity.
According to Dr. Chen, diabetes in pregnancy can be classified into two broad categories: preexisting diabetes, which is discovered before pregnancy, and gestational diabetes, which is when a pregnant person develops glucose intolerance during pregnancy, and then it resolves after delivery.
There are primarily two types of preexisting diabetes: Type 1, which is autoimmune in origin, and Type 2, which is related to metabolic syndrome.
There are also rare genetic forms of diabetes, such as maturity-onset diabetes of the young and latent autoimmune diabetes in adults.
“Gestational diabetes occurs when the placental hormones make a pregnant person more insulin resistant, and this leads to glucose intolerance during pregnancy. It typically resolves once the baby is delivered, but it’s very important to be aware that this condition increases the risk of Type 2 diabetes for the parent in the future,” says Dr. Chen.
Dr. Chen advises that it’s very important for anyone who is diagnosed with gestational diabetes to keep getting regular check-ups with their health care provider after delivery to make sure that they do not develop Type 2 diabetes in the future.
People typically do not notice any symptoms of diabetes until it is quite advanced, explains Dr. Chen.
In the beginning stages of diabetes, most people are asymptomatic. Once glucose levels start to get high, some typical symptoms include feeling very tired, feeling like you want to drink a lot more water, and urinating a lot more because of the high glucose levels in the urine.
When glucose levels get very high, people can also experience blurred vision and headaches.
“But unfortunately, typically, people do not really get any symptoms until things are quite advanced. This is why it is important for everyone to get regular check-ups with their health care providers, even when they are young, so that their glucose status can be checked on a regular basis,” says Dr. Chen.
Dr. Chen says that typically, gestational diabetes occurs during the second half of pregnancy.
“If a pregnant person has high glucose levels during the first half of pregnancy, from my experience, they actually have either preexisting diabetes or pre-diabetes, otherwise known as impaired glucose intolerance,” Dr. Chen explains.
The incidence is rising due to the obesity epidemic, says Dr. Chen.
“In the U.S. right now, the rate is about 8 percent of pregnancies; and in some areas of the country, it is even up to 10 percent,” he notes.
He says that the incidence of gestational diabetes is also especially high in countries on the Asian subcontinent, such as India and Bangladesh.
In the U.S., it is more prevalent among people who are African-American, Southeast Asian, Hispanic, and Native American.
Dr. Chen says that if someone has well-controlled diabetes before and throughout their pregnancy, there are generally no additional risks for the baby compared to the general population.
“For people with preexisting diabetes, we counsel them that their HbA1c at the time of conception should be as low as possible, at least below 7 percent.
“Studies have shown that higher HbA1c levels increase the risk of miscarriage and congenital malformations in early pregnancy. Specifically, the main congenital malformations we worry about are cardiac defects, kidney malformations, and neural tube defects,” Dr. Chen says.
Dr. Chen also explains that if glucose levels are not well controlled later in pregnancy, it can make the baby very large (macrosomic). When the mother’s glucose levels are too high, the baby’s developing pancreas produces more insulin to combat these high maternal glucose levels. It is the elevated fetal insulin levels that make the babies grow larger. This may then lead to an earlier delivery, particularly via cesarean section.
If glucose levels are not well controlled toward the end of pregnancy, the risk of the baby becoming hypoglycemic after they are born increases, and they may end up needing to be admitted to the neonatal intensive care unit (NICU). When these babies are born, their pancreases are still working very hard to produce a lot of insulin.
“The other things that can occur with babies born to mothers with poorly-controlled glucose levels are that they tend to be at greater risk of developing neonatal jaundice as well as getting infections such as neonatal pneumonia,” says Dr. Chen.
These babies are at increased risk of neonatal hypoglycemia, says Dr. Chen. So they always have their glucose levels checked very shortly after they are born. This is typically repeated again in three to four hours. If their levels are normal, then further monitoring is typically stopped.
“But if these levels are low, the baby would probably be admitted to the NICU. Hypoglycemia is dangerous in the newborn period because it can cause seizures,” Dr. Chen explains.
“Studies have shown that even if someone has very well-controlled diabetes during much of their pregnancy, it’s still very important when they come into labor and delivery that their glucose levels are still in a good range,” says Dr. Chen. “Typically, we like to keep these levels between 80 to 120 milligrams per deciliter at all times.”
If these levels drop too low, the mother becomes hypoglycemic, which would then increase stress on the baby.
And if the mother’s glucose levels get too high, this will make the baby produce more insulin, increasing their risk of neonatal hypoglycemia.
Dr. Chen says that most hospitals have a protocol when diabetic people are admitted for labor and delivery to ensure that their glucose levels are well controlled.
He explains, “If they are on insulin therapy, their doses are reduced (usually by about half) when they present, as they are not eating so much during this time, and they are also spending a lot of energy in labor.”
According to Dr. Chen, it’s important for anyone who develops gestational diabetes to go to regular follow-ups with their health care provider after delivery, as they are at increased risk of developing Type 2 diabetes in the future.
If someone with gestational diabetes was treated with diet and exercise, they should make sure that they get another oral glucose tolerance test (OGTT) around the time that their baby turns one.
If someone with gestational diabetes requires insulin therapy, then they should have the OGTT performed around six to eight weeks postpartum. Since this is when most people go for their postpartum OB-GYN check, it’s a good idea to have the OGTT test planned and scheduled for the same time.
Dr. Chen says that if these people want to get pregnant again in the future, it’s very important to have their glucose levels checked. If they do end up getting Type 2 diabetes or impaired glucose intolerance, it’s essential that they receive appropriate treatment before getting pregnant again.
“All of this will vastly improve the long-term health of the mother as well as the outcome of the next pregnancy,” Dr. Chen concludes.