Signs of Gestational Diabetes in Third Trimester, a Guide

Posted April 14, 2021 by Michael Chamberlain - See Editorial Guidelines

Gestational diabetes in the third trimester is a condition of glucose intolerance that begins or is first recognized during pregnancy.

According to the American Diabetes Association, Gestational diabetes affects nearly 10 percent of pregnant women. 

Let’s discover more about how you can work with your doctor to develop a plan to maintain a healthy pregnancy and find out the signs of gestational diabetes in third trimester.

Here’s the quick takeaway answer, but there are more details that we will cover throughout this article.

Signs of gestational diabetes in third trimester: Signs include increased thirst, a parched mouth regardless of how much you drink, a need to urinate more often, and overwhelming tiredness above that of a normal pregnancy. Gestational diabetes can sometimes have no signs at all, so clinicians will test for the condition.

With this short summary in mind, let’s start first by examining what the third trimester of pregnancy is. 

What is the third trimester of pregnancy? 

Signs of Gestational Diabetes in Third Trimester

A typical pregnancy normally lasts 40 weeks. These weeks are divided into three periods of three months, referred to as ‘trimesters’ that clearly define each stage of pregnancy. 

According to the UK’s NHS, the third trimester is between week 28 and 40 (to 41), with the second trimester being defined as between week 13 and week 27, and the first trimester as between week 1 and 12. 

Now that we can more easily understand when a pregnancy is in the third trimester, we can begin to understand signs of gestational diabetes to look for.

A blood test may identify gestational diabetes

A diagnosis of gestational diabetes mellitus, which doctors call GDM, in low-risk pregnant women is based on an oral glucose tolerance test, often referred to as OGTT by clinicians and ‘the orange drink’ by those who are pregnant. 

This test is administered in the third trimester, between 24 and 28 gestational weeks.

However, if there are risk factors such as obesity, then the test will be performed at an early stage in pregnancy. This includes any pregnant mothers whose BMI is over 40. 

The reason for this is to analyze the risk for thrombosis, which causes blood clots in your legs or lungs and may be offered to you as early as your first antenatal appointment. 

What is gestational diabetes? 

Gestational diabetes is high blood sugar that can develop during pregnancy and usually disappears after giving birth.

Insulin is the main hormone that is responsible for keeping blood sugar levels within a normal range.

During gestational diabetes, your body cannot produce enough natural insulin to keep up with rising blood sugar levels.

The main difference between the more usual kind of diabetes many suffer is that gestational diabetes it’s usually not present before pregnancy. 

Some women may only have GDM during one pregnancy, some during all of their pregnancies. 

Is gestational diabetes in third trimester common? 

Roughly 9.2% of pregnant women in the United States end up having gestational diabetes.

GDM can happen at any stage of pregnancy but is more common in the second or third trimester.

Although the test to diagnose gestational diabetes is currently performed in the third trimester, there is growing evidence to support that the fetus may be exposed to hyperglycemia before the current testing time frame, making earlier administration potentially advantageous.

Although the third trimester is currently the set time for the oral glucose test to be performed, new research is studying whether it would be beneficial for the test to be given at an early point in pregnancy, specifically 2nd trimester between 18-20 weeks. 

According to the above study, it’s suggested that an early diagnosis of GDM would play an important role in the prevention of short-term and long-term complications that affect both mothers and their children. 

However, within current clinical practices, a diagnosis of gestational diabetes is based mainly on detection in the third trimester. 

It is only then when therapy begins, so experts think that this may not be early enough to prevent complications from occurring. 

The same study researched whether pregnant women with GDM may potentially benefit from the result of the study by earlier diagnosis and management of the condition. 

At the time of writing, these are still preliminary tests and are inconclusive. 

What causes gestational diabetes? 

We know that the placenta produces hormones that help support the baby as it grows. In many cases, these hormones cause a build-up of glucose in the blood, and the mother’s pancreas cannot produce enough insulin to keep up with the glucose.

In other cases, insulin resistance may be the main issue.

Insulin resistance makes it hard for the mother’s body to use insulin. And this means that she may need up to three times as much insulin to compensate.

Whether the cause is not enough insulin or insulin resistance, it results in excess glucose in the bloodstream (hyperglycemia).

Related: How to Combat Insulin Resistance.

How do I know if I have gestational diabetes? 

Signs of Gestational Diabetes in Third Trimester

Most pregnant women don’t experience signs or symptoms of gestational diabetes. In fact, the only way to know is with a blood sugar test, typically given around 24 to 28 weeks gestation.

A few women may notice subtle signs and symptoms of gestational diabetes, including:

  • Increased thirst: You may feel like drinking more than normal, and having continual thirst that is difficult to quench may be a sign of gestational diabetes.
  • Overwhelming tiredness: Pregnant women will feel particularly tired in the first and third trimesters, given the extra demands on their body to grow and support a baby. However, gestational diabetes can make you feel even more tired than normal.
  • Dry mouth: A mouth that constantly feels dry or parched, even if you have been drinking water, can also be a sign of gestational diabetes.
  • Need to visit the toilet more often: With diabetes, excess sugar can end up in the urine, which then pulls more water from the body. This creates a greater need to urinate more frequently.

What are the health risks of Gestational diabetes in third trimester? 

If gestational diabetes is left untreated and unmanaged, it can pose complications and serious health risks to your baby. These include: 

  • Preterm birth and respiratory distress syndrome
  • Excessive birth weight
  • Low blood sugar at birth
  • Increased risk of type 2 diabetes later in life

Gestational diabetes risk factors

It’s just as important to know if you are considered high risk for gestational diabetes as it is to look for the signs and symptoms.

Certain women may be more likely to develop the condition, including:

  • Those with metabolic disorders 
  • Women older than 25 years old
  • Family history of type 2 diabetes
  • Prediabetes
  • Gestational diabetes in previous pregnancies
  • Overweight or obese
  • Non-white race

Further help for diabetes patients

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