1. Pregnancy
  2. Pregnancy health
  3. Complications

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Diabetes in Pregnancy: A Comprehensive Interview with Dr. Kenneth K. Chen

Diabetes in pregnancy can be present in two forms: pre-existing diabetes and gestational diabetes — the type that’s diagnosed for the first time during pregnancy. Today, Dr. Kenneth K. Chen speaks about these two categories of diabetes, how they can affect pregnancy, and what to do about it.

Diabetes in pregnancy can be classified into 2 broad categories: there is pre-existing diabetes, which is known before pregnancy, and gestational diabetes, which is when a pregnant person develops glucose intolerance during pregnancy, and then it resolves after birth. 

With respect to pre-existing diabetes, there are a few different types of pre-existing diabetes:  there is Type 1, which is autoimmune in origin, and Type 2, which is related to the metabolic syndrome, and specifically, this type is certainly increasing around the world, because more people of reproductive age are overweight and obese. And then, there are also rare genetic forms of diabetes as well, such as a form of diabetes called MODY, which is maturity-onset diabetes of the young; and LADA, which is 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. So, it is very important for anyone who is diagnosed with gestational diabetes to keep getting regular check-ups with their primary care doctor to make sure that they do not develop permanent Type 2 diabetes in the future. 

With diabetes, people typically do not really get any symptoms until it is quite advanced. In the beginning, most people are actually asymptomatic, but once the glucose level starts to get very very high, some typical symptoms that could occur are: people may feel very tired; people may feel that they want to drink a lot more water, and they have to urinate a lot more because of the high glucose levels in the urine.  

When the levels do get very high, people can also get 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 primary care doctors, even when they are young, so that their glucose status can be checked on a regular basis.

Typically, gestational diabetes is defined as occurring during the second half of pregnancy. If a pregnant person tests and gets high glucose levels during the first half of pregnancy; from my experience they actually have either pre-existing diabetes or pre-diabetes, otherwise known as impaired glucose intolerance.

Yes, the incidence is rising due to the obesity epidemic. In the U.S. right now, the rate is roughly about 8 percent of pregnancies; and in some areas of the country, it is even up to 10 percent.

The incidence is especially high in countries on the Asian subcontinent, such as India and Bangladesh.

In the U.S., it is more prevalent in African Americans, Southeast Asians, and Hispanics, as well as the Native American population.

I want to start by saying that if someone has well-controlled diabetes before and throughout their pregnancies; in general terms, there are no additional risks to the unborn child compared to the general population. 

For people with pre-existing diabetes, we counsel them that their HbA1c at the time of conception should be as low as possible, but it should at least be below seven 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. 

Later in pregnancy, if the glucose levels are not well-controlled, it can make the baby very large (macrosomic). What occurs is that when the mother’s glucose levels are 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 precipitate an earlier delivery, particularly via C-section.   

The other risk that occurs if the mother's glucose levels are not well controlled towards the end of pregnancy is that this increases the risk of the baby becoming hypoglycemic after they are born, and often they may end up needing to be admitted to the neonatal intensive care unit (NICU) for a period of time on intravenous glucose and special feeds.  The reason for this is that when these babies are born, their pancreas is 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. 

As I have discussed above, these babies are at increased risk of neonatal hypoglycemia. So they always have their glucose levels checked very shortly after they are born. This is typically repeated again in three to four hours’ time. If this level is normal, then all further monitoring is 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.

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. 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 at that time, and this will increase the risk of the baby getting neonatal hypoglycemia.

Most hospitals do have a protocol regarding when diabetic people are admitted for labor and delivery to ensure that their glucose levels are well-controlled. 

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.

It is most important that anyone who develops gestational diabetes undergo close medical follow-up in the future, 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 test tolerance (OGTT) performed around the time that their baby turns one.  

If someone with gestational diabetes requires insulin therapy, then they should have this OGTT performed at around six to eight weeks postpartum. They would usually have their routine postpartum OB-GYN check done at this time, and so it would be best to ask them to have this performed then so that it isn’t forgotten in the midst of their busy schedules. 

If these people want to get pregnant again in the future, it’s very important for them to have these glucose levels checked, because if they do end up getting permanent Type 2 diabetes or impaired glucose intolerance, it’s essential that they receive the appropriate treatment before they get pregnant again. All of this will vastly improve the long-term health of the mother as well as the outcome of the next pregnancy.

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