Introduction

Brief overview about GDM

GESTATIONAL DIABETES MELLITUS (GDM) is a form of diabetes that occurs in pregnancy (high blood glucose concentration in an expectant woman). Usually, it occurs in the third trimester. The cause is thought to be due to pregnancy hormones from the placenta interfering with insulin action on insulin receptors. These hormones can also block the ability to make insulin. This medical condition seems to be due to pregnancy.

Gestational diabetes is believed to be type 4 diabetes mellitus. Other classifications are:

• Type 1: Lack of/ inadequate insulin
• Type 2: Insulin insensitivity or resistance
• Type 3: Alzheimer’s disease
• Type 5: Malnutrition-related DM

In accordance with the World Health Organization (WHO) guidelines;

 Fasting blood glucose:

1. Normal: 70-100 mg/dL (3.9-5.6 mmol/L)
2. Pre-diabetes: 100-125 mg/dL (5.6-6.9 mmol/L)
3. Diabetes: ≥126 mg/dL (≥7.0 mmol/L) (on two separate tests)

 

Random blood glucose:

1. Normal: <140 mg/dL (<7.8 mmol/L)
2. Pre-diabetes: 140 to 199 mg/dL (7.8 to 11.0 mmol/L)
3. Diabetes: ≥200 mg/dL (≥11.1 mmol/L)

 

Key Facts & Statistics

Key facts and statistics that surround GDM

• In the USA, data from the US Centers for Disease Control and Prevention (CDC) states that almost 10 out of 100 pregnant women will develop gestational diabetes.
• Globally, the average rate of GD is around 17%.
• In 2021, around 21,100,000 live births (16.7%) had some form of hyperglycemia during pregnancy. This situation is more common in LMIC (low and middle income countries) with limited access to maternal healthcare.

 

 Risk Factors

What are the risk factors for GDM ?

 

Any expectant woman can develop gestational diabetes mellitus. There are several risk factors for this. These are:

• Hypertension.
• Being overweight or having obesity.
• Gestational diabetes in previous pregnancies.
• Family history of type 2 DM.
• Prediabetes (history of hyperglycemia).
• Advanced maternal age.
• Polycystic ovarian syndrome (PCOS).
• Age. Being 45 years or older.
• Racial background. Being a native American or Hispanic.
• Physical inactivity.

 

 Causes

What are the causes of GDM?

The exact cause(s) is not yet established.

Hormonal changes during pregnancy are believed to affect the mechanisms of action of insulin.

Insulin is a peptide hormone secreted from beta cells which are located at the center of the islets of langerhans. Insulin ensures that glucose is delivered from bloodstream into the cells for use. When insulin is interfered with, glucose concentration in the blood builds up. This is referred to as hyperglycemia and it leads to development of diabetes.

 

In pregnancy, placental hormones can interfere with the mechanism of action of insulin leading to elevated blood sugar levels, which in pregnancy translate to GDM. These placental hormones thought to have a blocking effect on insulin are; estrogen, human placental lactogen and cortisol. This phenomenon is called contra-insulin effect, and it begins to develop at about 20-24 weeks of gestation.

 

As the placenta grows and develops, greater quantities of these hormones are produced and this leads to raised chances of insulin resistance. Usually, the pancreas can make additional insulin to overcome this resistance. However, when the production of insulin is not able to overcome the effect of placental hormones, GDM happens.

 

 Signs & Symptoms

What are the signs and symptoms of GDM?

 

• Polyuria (excessive urination).
• Polydipsia (increased thirst).
• Fatigue (Tiredness).
• Nausea.
• Frequent infections such as yeast infections.
• Blurred (unclear) vision.

 

 

 Diagnostic Procedures & Tests

How is GDM diagnosed?

 

Tests for GDM are performed around the 24^th to 28^th weeks of gestation since most physicians believe that it is the best time to get the most accurate results.

For persons with increased risk factors for the condition, screening can be performed a little bit earlier.

 

• Glucose challenge test. It is also known as a glucose screening test or a one-hour glucose tolerance test. A carbohydrate-containing sweet liquid is drank by the patient and she is instructed to wait for 1 hour. Then a blood sample is drawn from her arm and blood glucose levels measured. If the result shows very high concentration, a glucose tolerance test will be ordered.
• Glucose tolerance test. It is performed when the glucose challenge test shows irregular results. It is also called 2-hour or 3-hour glucose challenge test. Fasting for at least 8 hours is recommended.The healthcare worker will draw a sample of blood before and at one-, two- or three-hour intervals after the drink has been taken. This test can be used to confirm a diagnosis of GDM in a pregnant woman.

 

 

 Treatment and Management

How is GDM treated?

• Non-pharmacological interventions. These are: frequent physical activity, dietary changes and regular monitoring of blood glucose levels, at least 4 times per day.
  

  A pregnant woman checking her blood sugar levels.

• Pharmacological treatment. This approach uses medicines. Here, insulin is the main drug, especially for patients in whom non-pharmacological therapies have failed to work appropriately. Sometimes, oral agents can be used to lower blood glucose. They include metformin (a biguanide) and glyburide/ glibenclamide (a sulfonylurea).

 

 Complications

What are the complications of GDM?

 

This condition puts the mother and her fetus at risk of facing complications.

For the mother, gestational DM raises the risk of:

•  Caesarean section (if the fetus develops to become too big within the uterus).
• Pre-eclampsia (hypertension in pregnancy).
• Persons with gestational DM have slightly raised chances of developing type 2 DM later in life.

 

For the baby, GDM (gestational diabetes mellitus) increases the risk for:

•  Breathing difficulties at birth.
•  Low blood glucose concentration. In newborn children, hypoglycemia can cause seizures.
•  Raised birth weight.
•  Obesity.
•  Premature birth (preterm birth).
•  Development of type 2 DM later in their life.
•  Stillbirth. Untreated GDM can result in fetal demise before or shortly after the birth of the baby.

 

Prevention

How to lower chances of developing GDM

There are several strategies that can be taken to reduce risk of developing GDM. The condition is not entirely preventable.

To lower GDM risk:

• Consume healthy foods. Eat high-fat, low-calorie diet.
• Embrace physical activity. Engage in regular physical exercises such as swimming, running or walking for 30 minutes to hour on most days of the week.
• Plan to conceive while having a healthy weight. Lose any extra weight before becoming pregnant. This will help to have a healthy pregnancy.

 

 

Living With GDM

For persons already suffering from GDM, a management plan should be part of their daily routine.

The following can be done:

• In every week, they should put aside at least 30 minutes of exercise.
• Check blood glucose levels each day, at the same time.
• Visit the doctor or a diabetes educator on information about tips for daily management of GDM.