Gestational Diabetes Mellitus

Gestational diabetes mellitus is the name for the condition if glucose intolerance starts or is found for the first time during pregnancy (GDM). On average, GD manifests itself between the 24th and 28th week of pregnancy.

Last Updated: February 26, 2024

The Irish Neonatal Health Alliance finds that one or two in 10 women have gestational diabetes. Filipino women commonly develop GDM. About 40.4% of high-risk women tested positive for GDM after 26 weeks of gestation.

Why some women develop gestational diabetes remains unknown. Pre-pregnancy weight gain is a factor. Most of the time, different hormones work to keep blood sugar levels steady, but hormone levels fluctuate during pregnancy, making it tougher to process blood sugar. As a result, blood sugar increases.

Experts also found risk factors for a woman to develop GDM. The following includes:

  • Obesity
  • Inactivity
  • Having diabetes prior to pregnancy
  • Previous gestational diabetes
  • Having PCOS
  • A diabetic relative.

During pregnancy, women with diabetes seldom have any symptoms. However, some women go through:

  • Frequent urination;
  • Nausea;
  • Thirst;
  • Tiredness.

In the 24th to 28th week of pregnancy, your doctor will check for gestational diabetes. However, if a woman has a high risk of diabetes, like being overweight or obese before pregnancy, if any of the parents, siblings, or child has diabetes, or had gestational diabetes during a previous pregnancy, the physician may test for diabetes early in the pregnancy, probably at the first prenatal visit.

During pregnancy, blood sugar will be monitored by your doctor. There are two parts to the exam:

  • Glucose Challenge Test. Patient will drink a sweet beverage for the glucose challenge. Her blood sugar level will be checked after an hour. The doctor will then order a glucose tolerance test if blood sugar is high.  
  • Glucose Tolerance Test. Oral glucose tolerance test is done only if the challenge test results are out of the ordinary. Before taking the tolerance test, the patient will need to fast for eight hours. The doctor takes a blood sample before and after you consume a sweet beverage. Diabetes in pregnancy can be diagnosed through this tolerance test. 


Glucose monitoring, increased physical activity, and dietary changes are the cornerstones of non-pharmacologic care of gestational diabetes. 30 minutes of moderate-intensity aerobic activity five days a week is recommended for GDM.

If glycemic control is inadequate despite diet and exercise, pharmacologic therapy is advised. Insulin is the first-line GDM treatment. When optimal glucose levels cannot be achieved by food and exercise, insulin therapy has been regarded as the mainstay approach for gestational diabetes care.

Even though the FDA hasn't approved them, more and more women with gestational diabetes are taking metformin and glyburide by mouth. Glyburide can be given in doses as low as 2.5 mg and as high as 20 mg. The first dose of metformin should be 500 mg, and the highest dose is 2500 mg.

Staying healthy before and during pregnancy can lower a woman's risk of developing gestational diabetes. It is also recommended to maintain an active lifestyle and eat healthily. Ways to control blood glucose through diet includes:

  • Don't eat fast food, processed foods, or drinks with a lot of sugar;
  • Choose a balance of proteins, carbohydrates, fiber, and fats;
  • Eat more small meals than big ones
  • Plan to eat at the same time, every day.

It is important to note that our body uses more glucose when we exercise, which may lower blood sugar. Lastly, incorporate diabetes care into a regular routine, through creating a schedule and sticking to it. Most importantly, a daily routine of checking blood sugar levels should be maintained.


Quintanilla Rodriguez BS, Mahdy H. Gestational Diabetes. [Updated 2022 Sep 6]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2022 Jan-. Available from:

National Nutrition Council (2022). Diabetes and Pregnancy. Retrieved November 2, 2022, from

Cleveland Clinic (2022). Gestational Diabetes. Retrieved November 2, 2022, from

Mayo Clinic (2022). Gestational Diabetes. Retrieved November 2, 2022, from

Last Updated: February 26, 2024