What is Gestational Diabetes and How Is It Managed?

One of the most common complications during pregnancy is gestational diabetes, affecting up to 25 percent of pregnancies globally. This is a specific type of diabetes—abnormal blood sugar regulation—that only starts during pregnancy and typically resolves after childbirth. However, having gestational diabetes (GD) can increase health risks to both pregnant parent and baby, which makes prevention and treatment critical for better health outcomes. 

What is diabetes?

When you eat sugar (or carbohydrates that break down into sugar), your pancreas releases the hormone insulin. Insulin sends a signal to your cells to open the gates and allow glucose (sugar) to enter so it can be used as a fuel source for the cell. But, if there’s not enough insulin around, or if your cells aren’t responding to the insulin signal, then glucose is locked out of the cells and remains in the blood stream, leading to high blood-sugar levels. Plus, cells can only hold so much glucose, so if your diet is rich in sugar or non-fiber carbohydrates, the cell’s capacity can be overloaded, leaving all that extra glucose in the bloodstream, or having it return to the liver where it can get stored as fat. Having poor blood-sugar regulation and chronically high blood-sugar levels can lead to a diagnosis of diabetes.

There are four types of diabetes:

• Type 1: When the pancreas doesn’t make insulin. Type 1 diabetes is an autoimmune condition, meaning that the person’s immune system destroys the pancreatic cells that make insulin. This is usually diagnosed in childhood or adolescence and requires life-long insulin treatment.

• Type 2: When the pancreas doesn’t make enough insulin or, the body’s cells don’t respond to the insulin signal very well (insulin resistance). This happens more commonly in those who are obese, have high sugar and processed carbohydrate diets, and who are sedentary (no exercise). About 90 percent of diabetics are type 2, and this is most common in those aged 40 to 59 years old, but the rates in those aged 15 to 39 is increasing.

• Prediabetes: Indicates a risk of developing type 2 diabetes due to higher-than-normal blood sugar levels or insulin resistance.

• Gestational diabetes: When diabetes develops in pregnancy in someone who did not previously have diabetes—more on this below.

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What happens in gestational diabetes?

 During pregnancy, the body becomes more sensitive to insulin so you can use or store more glucose—like building an energy reserve to be used during your pregnancy. However, the placenta wants that glucose for the fetus, so surging hormones from the placenta support a more insulin-resistant state to keep more glucose in the blood stream so that it can be used for fetal growth. This is where higher blood sugar levels in pregnancy come from.
 
Your body looks at this activity from the placenta and is supposed to compensate by pumping up the cells in the pancreas that release insulin so they can send out more when there is sugar present. But, if that doesn’t happen, blood sugar levels will get too high—diabetic high—and this is the cause of GD.

How do I know if I have gestational diabetes? 

Gestational diabetes can be detected around 13 to 26 weeks of pregnancy or in early third trimester, so that’s around the time your doctor or midwife will send you for an oral glucose tolerance test (OGTT) to see how your body is responding to glucose.

Oral Glucose Tolerance Test (OGTT) 

For this test you’ll be asked to fast (typically no food or drinks for about eight to 12 hours) before going to the lab. At the lab, you’ll be provided a very sugary drink to consume. You’ll need to wait one to two hours before having your blood drawn and measured—doctors are looking for the amount of glucose remaining in your blood. This can determine how well your body responds to ingested sugars and if insulin is functioning well enough to keep blood sugar levels normal.

Who is at risk of getting gestational diabetes?

There’s a higher risk of developing GD if you were overweight or obese pre-pregnancy, had a poor quality diet (high in refined carbohydrates and sugars), were physically inactive, have polycystic ovary syndrome (PCOS) or were insulin resistant pre-pregnancy. And while all of these can indicate a higher likelihood of developing GD, there are cases where none of these factors are present, and GD still develops. There are genetic factors to consider that may also contribute to a higher risk of having GD, including if you have a first-degree relative with type 2 diabetes. Certain ethnicities (including those who are Asian or Hispanic) are also at greater risk, as are those 40 or older. That said, GD can develop in any pregnancy, which is why it is screened for in every pregnancy.

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What are the risks of having gestational diabetes?

For babies

It can lead to abnormally high birth weight, preterm birth, developmental malformations, neurological development and neonate respiratory distress in newborns. It also increases the risk of obesity and the development of diabetes during childhood and beyond.

For the pregnant person

Having GD increases the risk of developing high blood pressure and pre-eclampsia, a serious condition that involves high blood pressure and protein in the urine. Having GD also increases the risk of developing type 2 diabetes and obesity later in life.

How is gestational diabetes treated?

Dietary changes are the main therapeutic treatment of GD. Some of the recommended guidelines include:

• Eat three small-to-moderate-sized meals and two-to-three snacks per day that are balanced with fiber-rich carbohydrates, protein and unsaturated fats.
• Keep breakfast lower in carbohydrates (30g or less) compared to lunch and dinner.
• Meals in general should consist of low-glycemic index (low-GI) and plant-based foods.
• Pair carbohydrates with a lean protein or healthy fats (like avocado, olive oil, eggs, and nuts or seeds).
• Have a (healthy) bedtime snack to keep the body out of ketosis.

Women with GD are also recommended to participate in 30 minutes of moderate-intensity physical activity five days a week (or 150 minutes per week). Even going for a brisk walk after a meal can improve post-meal blood sugar regulation.

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If diet and exercise alone don’t regulate blood glucose levels, insulin may be prescribed. This is the first-line drug treatment since the insulin doesn’t significantly cross the placenta compared to other blood-sugar lowering drugs such as glyburide and metformin.

Can gestational diabetes be prevented?

Prevention of GD starts with pre-pregnancy health: reducing the incidence of obesity, keeping a healthy Mediterranean-style diet and regularly participating in exercise. Following these guidelines before the week 15 of pregnancy has been reported to decrease the risk of GD by 18 percent.
 
Certain dietary supplements can also help in the prevention of GD. For example, giving females with GD  Vitamin D (1000 to 4762IU) daily was shown to improve blood sugar regulation and reduce fasting blood glucose levels.