Gestational Diabetes and Type 2 Diabetes - What’s the difference and how are they connected?
Key Takeaways
Gestational diabetes is a problem with blood sugar control that can develop during pregnancy.
In Singapore, about 15 to 20% of pregnant women develop gestational diabetes.
In women with gestational diabetes, the body is insulin resistant, meaning that it can’t respond normally to insulin, the hormone that lowers blood sugar.
Gestational diabetes is caused by the hormonal changes of pregnancy, which cause the body to become insulin resistant.
Type 2 diabetes also involves insulin resistance, but this has other causes, such as hormones produced by adipose tissue and chronic inflammation.
Gestational diabetes usually resolves after the baby is born, but in some cases, it may persist and become type 2 diabetes.
About 50% of women with gestational diabetes will go on to develop type 2 diabetes at some point in their lives.
What is gestational diabetes?
Gestational diabetes is a problem with blood sugar control that can develop during pregnancy. It’s also known as gestational diabetes mellitus, or GDM. In women who develop gestational diabetes, it starts during the second trimester of pregnancy, and generally becomes more severe as the pregnancy progresses.
In women with gestational diabetes, the body becomes resistant to the effects of insulin. Insulin is a hormone that helps to keep blood sugar from rising after a meal. In women with gestational diabetes, the body is not able to respond normally to insulin. Because of this, blood sugar levels can rise too high, which can cause health complications in both the baby and the mother.
This condition is relatively common. In Singapore, research has found that gestational diabetes affects about 15 to 20% of all pregnant women. Because it’s so common, it’s recommended that all pregnant women receive screening for gestational diabetes between 24 and 28 weeks of pregnancy. This allows the condition to be detected early, so that appropriate treatment can be started.
Difference between gestational diabetes and type 2 diabetes
Both gestational diabetes and type 2 diabetes involve insulin resistance, meaning that the body is not able to respond normally to insulin. In this way, the two conditions are similar. However, there are some differences.
Timing of the condition
Gestational diabetes occurs during pregnancy, while type 2 diabetes occurs in those who are not pregnant. If a woman already has type 2 diabetes before she falls pregnant, then this would not be considered to be gestational diabetes during her pregnancy. Instead, it would be pre-existing type 2 diabetes. (The same is true for women who have type 1 diabetes before pregnancy.)
There are some cases where a woman has undiagnosed diabetes before she falls pregnant, meaning that she didn’t know that she had diabetes. In this case, type 2 diabetes may initially be misdiagnosed as gestational diabetes. To help avoid this, it’s recommended that women who are at a higher risk for type 2 diabetes receive screening in the first trimester. This is before gestational diabetes develops, so if this test is positive, it generally means that the mother has type 1 or type 2 diabetes.
Cause of insulin resistance
Although both conditions do involve insulin resistance, the mechanism that leads to insulin resistance is somewhat different in gestational diabetes and type 2 diabetes.
Gestational diabetes is caused by hormonal changes that occur during pregnancy. Certain hormones tend to make a pregnant mother’s body more resistant to insulin. Some of these are produced by the placenta, the tissue that supports the baby while it’s in the womb. These include human placental lactogen (hPL) and human placental growth hormone (hPGH). Others are normally produced by the mother’s body, but are produced at higher levels during pregnancy. These include estrogen, progesterone, and cortisol.
Because of these hormonal changes, all pregnant women experience some level of insulin resistance. In most women, the body is able to produce extra insulin to compensate. This allows blood sugar to stay relatively well controlled. However, some women experience more severe insulin resistance, and the body can’t produce enough insulin to compensate. This causes gestational diabetes.
In people with type 2 diabetes, researchers are still working to better understand exactly why insulin resistance develops. There are believed to be several factors that play a role:
Hormones may also be important in type 2 diabetes. Adipose tissue (fat tissue) produces certain hormones, and these can cause insulin resistance. When there are larger amounts of adipose tissue in a person’s body, higher levels of these hormones are produced.
Chronic inflammation, in which the body’s immune response is constantly activated at a low level, can also impact tissues and lead to insulin resistance.
Substances produced during exercise help to maintain insulin sensitivity throughout the body. When a person doesn’t get enough exercise, these substances are not produced, which can cause the body to become insulin resistant.
Keeping gestational diabetes under control
It’s essential to keep blood sugar under control as much as possible during the pregnancy. When not properly treated, gestational diabetes can cause significant health problems for both the mother and the baby. Keeping blood glucose levels under control greatly reduces the risk of complications.
The first step is for the woman to monitor her blood sugar regularly. At a minimum, glucose levels should be checked each morning before eating, and one to two hours after each meal. Treatment will be adjusted to help keep these glucose levels as close to the normal range as possible. Glucose levels can be checked with a traditional glucometer, which uses a finger prick to collect a drop of blood for testing, or with a continuous glucose monitor (CGM), which is worn on the arm and checked with an app on your smartphone. A CGM is more convenient and allows glucose levels to be monitored more closely.
If blood sugar levels are too high, a number of different treatments may be used. In some cases, more than one treatment is needed to achieve good blood sugar control. Options include:
Lifestyle changes, including increased physical activity and a healthy diet. The support of a health coach can be very helpful in achieving this.
Managing weight gain to keep it within a normal range. Of course, gaining weight during pregnancy is normal and healthy, but gaining too much weight can increase insulin resistance.
Oral medications that help to improve insulin sensitivity, such as metformin.
Insulin therapy. This involves giving extra insulin through injections or an insulin pump, to overcome insulin resistance and bring blood sugar back into a more normal range.
These are similar to the treatments used for type 2 diabetes, but doctors must consider the effects of any potential medication on the baby. In many cases, there is not enough evidence to be sure that certain medications are safe to use during pregnancy. Because of this, medication options may be different for those with gestational diabetes than they are for those with type 2 diabetes.
Can gestational diabetes lead to type 2 diabetes?
In most cases, gestational diabetes will go away after the baby is born. As the hormonal changes of pregnancy fade, the mother’s body will usually stop experiencing insulin resistance, and will once again be able to keep blood sugar under control.
However, there are some cases where this does not occur, and the woman continues to have high blood sugar levels after the pregnancy is over. Blood sugar levels should return to normal within 12 weeks after delivery of the baby. If this doesn’t happen, the mother would be considered to have developed type 2 diabetes.
To make sure that blood sugar control has returned to normal, it’s recommended for a woman with gestational diabetes to have another oral glucose tolerance test about 6 to 12 weeks after the birth. If the results show normal blood glucose levels, this means that her gestational diabetes has resolved as expected. If the levels are still high, then she may have developed type 2 diabetes, although further testing may be needed to be sure.
Can gestational diabetes lead to type 2 diabetes later in life?
Even when gestational diabetes does go away after the baby’s birth, it’s still important for the woman to watch out for potential problems with blood sugar control in the future. This is because having gestational diabetes significantly increases a woman’s risk of later developing type 2 diabetes. In fact, about 50% of all women with gestational diabetes will go on to develop type 2 diabetes later in their lives.
Because of this, if you develop gestational diabetes during one or more pregnancies, it’s important that you continue to receive screening for type 2 diabetes throughout your life. The Ministry of Health recommends that women who have had gestational diabetes receive screening for diabetes at least once every three years, and preferably every year.
Support in managing diabetes
Whether insulin resistance is caused by gestational diabetes or type 2 diabetes, lifestyle changes are an important part of treatment. Many people find it helpful to have the support of an expert team to develop and maintain a healthy lifestyle plan. Monitoring by a physician is always important for people with any type of diabetes, and having a health coach can also be extremely valuable.
Learn more about NOVI Magnum, our holistic Diabetes Treatment Program.