Gestational diabetes affects 18.4 million women globally. Diabetes symptoms in pregnancy due to less insulin production include frequent thirst and urination.

Diabetes (Gestational)

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Ismail Munir

Overview

According to the National Institute of Health (NIH), gestational diabetes is a type of diabetes that develops during pregnancy<a href="#accordion">[1]</a>. It is the most common metabolic disorder of pregnancy, affecting 7-10% of all pregnancies worldwide<a href="http://#accordion">[2]</a>.

A study conducted by Aga Khan University reported that the average prevalence of gestational diabetes has more than doubled from 8.1% to 17.8% between 2005 and 2018<a href="#accordion">[3]</a>. This is likely due to the increasing levels of obesity and type 2 diabetes among the population. As per the International Diabetes Federation&#39;s latest figures, Pakistan has the highest national prevalence of <a href="https://https://merisehat.pk/disease/diabetes-type-1-and-2">diabetes</a> in the world<a href="#accordion">[4]</a>.&nbsp;

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Although gestational diabetes mellitus (GDM) has progressively increased over the years, the exact prevalence of the disease in Pakistan remains unclear. Moreover, due to differences in risk factors and diagnostic criteria, the prevalence varies among the various provinces. Nevertheless, metabolic disease poses significant risks to both maternal and fetal health. Therefore, there is a need for effective screening and awareness programs among pregnant women.

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Signs And Symptoms

Gestational diabetes is typically diagnosed between 24 and 28 weeks of pregnancy. However, pregnant women do not generally experience any symptoms. At most, one can experience increased thirst and frequent urination. 
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Causes

Typically, the pancreatic beta cells produce the hormone insulin. Insulin helps cells take up glucose and utilize it for energy. Thus, maintaining blood glucose levels within the normal range.&nbsp;

During pregnancy, the placenta produces various hormones needed for fetal growth and the continuation of pregnancy, such as human placental lactogen. These hormones make the cells resistant to insulin. Moreover, the weight gain associated with pregnancy further contributes to insulin resistance. Although normally the beta cells compensate for the insulin resistance by producing more insulin, in pregnancy this might not occur. Therefore, the glucose begins to accumulate in the blood, causing hyperglycemia and leading to the development of gestational diabetes.&nbsp;

However, it remains unclear why some women develop gestational diabetes and others don&#39;t.

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A screening test is usually conducted during the second trimester (24-28 weeks) in women at average risk of gestational diabetes. However, those at high risk may be tested at their first prenatal visit. Screening tests include:

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Initial Glucose Challenge Test - Also called the glucose screening test, it involves drinking a 50g glucose solution. After one hour, a blood sample is taken to check the blood glucose levels. Levels higher than 140mg/dl indicate a high risk of gestational diabetes. If a person&#39;s reading comes high, the test is followed by a glucose tolerance test to determine whether they have gestational diabetes.&nbsp;

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Oral Glucose Tolerance Test (OGTT) - Women must be present in a fasting state for the test. First, a blood sample is taken for the fasting blood glucose reading. Then, similar to the glucose challenge test, one must drink a 100g glucose solution. Next, blood is tested every hour for a total of 3 hours. If at least two of the blood sugar readings are higher than the normal range, then the person has gestational diabetes.

Often doctors might skip the glucose challenge test and directly perform a 75g OGTT test. This is called a one-step approach. It involves the patient drinking a 75g glucose solution instead of 50g. Measurements are taken in the fasting state, and at 1- and 2-hours post-solution.

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Diagnosis

In Pakistan, the International Association of Diabetes and Pregnancy Study Groups (IADPSG) 2010 criteria are often implemented for diagnosing gestational diabetes<a href="#accordion">[5]</a>. It is based on the one-step approach. As per the criteria, a diagnosis of gestational diabetes is made if any one of the following is met:

<ul>
	<li>Fasting Blood Glucose: 92mg/dl or above</li>
	<li>75g-OGTT at 1 hour: 180mg/dl or above</li>
	<li>75g-OGTT at 2 hours: 153 mg/dl or above</li>
</ul>

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The American Congress of Obstetricians and Gynecologists (ACOG) recommends the two-step approach for diagnosing GDM<a href="#accordion">[6]</a>. The two-step approach involves the initial glucose challenge test followed by the 100g OGTT test. A diagnosis of GDM is made if at least two of the following are met:

<ul>
	<li>Fasting Blood Glucose: 95mg/dl or above</li>
	<li>50g-OGTT at 1 hour: 180mg/dl or above</li>
	<li>50g-OGTT at 2 hours: 155mg/dl or above</li>
	<li>50g-OGTT at 3 hours: 140mg/dl or above</li>
</ul>

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Treatment

Treatment of gestational diabetes involves a combination of lifestyle changes, blood sugar monitoring, and medications, if necessary. Treatment aims to keep blood glucose levels within the normal range.&nbsp;

For women with gestational diabetes, the recommended daily targets of blood glucose levels are<a href="#accordion">[7]</a>:

<ul>
	<li>Fasting plasma glucose levels: less than 95mg/dl</li>
	<li>1-hour postprandial glucose levels: less than 140mg/dl</li>
	<li>2-hour postprandial glucose levels: less than 120mg/dl</li>
</ul>

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Treatment for gestational diabetes includes:

Blood Sugar Monitoring - A glucose meter can help women track their blood glucose levels. Most doctors recommend taking readings before and after meals, at bedtime, and in the morning after waking up.&nbsp;

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Lifestyle Changes - An experienced dietician can help patients create diet plans that are based on their blood sugar targets, exercise habits, pregnancy weight goals, blood sugar levels, and dietary habits. A balanced diet consisting of whole grains, proteins, fruits, and vegetables can help keep blood glucose levels within the normal range. Other than a healthy eating plan, regular exercise is also important for lowering blood sugar and preventing complications. However, any form of exercise or physical activity should be started after consultation with one&#39;s healthcare team.&nbsp;

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Medications - If a healthy diet and exercise are unable to maintain glucose levels within a normal range, doctors may recommend pharmacological therapy. Insulin is the first choice for treating hyperglycemia associated with gestational diabetes. Other drugs such as metformin and sulfonylureas can cross the placenta and are not recommended. Both can cause hypoglycemia in the fetus.

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Hyperglycemia can have adverse effects on both maternal and fetal health.&nbsp;

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<h5 dir="ltr">Maternal Complications&nbsp;</h5>

In mothers, elevated blood glucose levels can lead to several adverse outcomes. These include:&nbsp;

<ul>
	<li>Preeclampsia is a serious pregnancy complication that develops due to high blood pressure. It is characterized by proteins in the urine, swelling of the legs and feet, headaches, and blurry vision.&nbsp;</li>
	<li>Approximately half of women with GDM go on to develop type 2 diabetes, especially 5-10 years after delivery<a href="#accordion">[8]</a>. Moreover, compared to women without GDM, women with gestational diabetes have a 10-fold increased risk of developing type 2 diabetes<a href="#accordion">[7]</a>. There is also an increased risk of developing gestational diabetes in future pregnancies.</li>
	<li>Increased risk of delivery via cesarean section.</li>
</ul>

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<h5 dir="ltr">Neonatal Complications</h5>

Children born to mothers with gestational diabetes can have the following complications:

<ul>
	<li>Hypoglycemia&nbsp;is the most common neonatal complication and occurs shortly after birth. It can lead to seizures in the baby</li>
	<li>Higher-than-normal birth weight (9 pounds or more) can lead to obstructed labor and birth injuries such as shoulder dystocia.</li>
	<li>Breathing difficulties</li>
	<li>Increased risk of preterm birth</li>
	<li>Increased risk of developing type 2 diabetes in the future</li>
</ul>

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Moreover, there is a higher risk of congenital anomalies and stillbirth in neonates.

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The following increases one&#39;s risk of gestational diabetes:

<ul>
	<li>Family history of <a href="https://merisehat.pk/disease/diabetes-type-1-and-2">type 2 diabetes</a></li>
	<li>Age greater than 25 years</li>
	<li>Belonging to African American, Asian, Hispanic, or American Indian race or ethnicity</li>
	<li>History of gestational diabetes</li>
	<li>Have prediabetes</li>
	<li>Overweight before pregnancy</li>
	<li>Diagnosed with <a href="https://merisehat.pk/disease/polycystic-ovary-syndrome-pcos">polycystic ovary syndrome</a></li>
	<li>History of miscarriage or stillbirth</li>
	<li>Given birth to a baby weighing more than 9 pounds</li>
</ul>

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Shortly after birth, a woman&#39;s blood glucose levels return to normal. However, due to an increased risk of type 2 diabetes, they should undergo lifelong screening for diabetes every 1 to 3 years. As per the recommendations of the American Diabetes Association (ADA), 6-12 weeks after birth, women with GDM should undergo 75g-OGTT, <a href="https://merisehat.pk/disease/hypertension-57">blood pressure</a> monitoring, BMI measurement, and other postpartum care<a href="#accordion">[9]</a>. In case of impaired glucose tolerance, a healthcare professional should be sought to provide lifestyle interventions. Moreover, the baby is also monitored for risk of complications.

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Women can lower their risk of gestational diabetes prior to getting pregnant. This is achieved by eating a healthy diet, losing weight if overweight, and daily exercise.&nbsp; 
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Key Points

<ul>
	<li>During pregnancy, the placenta produces hormones that increase insulin resistance. The pancreatic beta cells are unable to compensate and as a result, glucose accumulates in the blood. Thus, resulting in the development of gestational diabetes mellitus (GDM).</li>
	<li>GDM can result in both maternal and neonatal complications. In neonates, gestational diabetes can cause hypoglycemia, excessive birth weight, shoulder dystocia, breathing difficulties, and an increased risk of stillbirths. On the other hand, mothers with GDM can develop type 2 diabetes in the future and are at risk of developing preeclampsia during pregnancy.</li>
	<li>Gestational diabetes is typically diagnosed between 24 to 28 weeks of pregnancy using the glucose challenge test and oral glucose tolerance test (OGTT).</li>
	<li>Treatment of GDM involves a combination of dietary changes, physical activity, glucose monitoring, and diabetic medications. Insulin is the first choice for use in GDM while metformin and sulfonylureas are contraindicated.&nbsp;&nbsp;</li>
</ul>

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[1] NIH, 2017. Definition & Facts of Gestational Diabetes. [Online]

[2] Nguyen, C. L. et al., 2018. Prevalence of Gestational Diabetes Mellitus in Eastern and Southeastern Asia: A Systematic Review and Meta-Analysis. Journal of diabetes research.

[3] Sheikh, A. & Sheikh, L., 2020. Changing prevalence of gestational diabetes mellitus during pregnancy over more than a decade. The Journal of the Pakistan Medical Association, 70(8).

[4] International Diabetes Federation, 2021. With 1 in 4 adults living with diabetes, Pakistan has highest diabetes prevalence in the world. s.l.:s.n.

[5] International Association of Diabetes and Pregnancy Study Groups Consensus Panel, 2010. International Association of Diabetes and Pregnancy Study Groups Recommendations on the Diagnosis and Classification of Hyperglycemia in Pregnancy. Diabetes Care, 33(3), pp. 676-682.

[6] Rani, P. R. & Begum, J., 2016. Screening and Diagnosis of Gestational Diabetes Mellitus, Where Do We Stand. Journal of Clinical and Diagnostic Research, 10(4).

[7] American Diabetes Association, 2021. Management of Diabetes in Pregnancy. In: Standards of Medical Care in Diabetes. s.l.:s.n.

[8] International Diabetes Federation, 2020. Gestational Diabetes.

[9] Martinez, N. G., Niznik, C. M. & Yee, L. M., 2017. Optimizing Postpartum Care for the Patient with Gestational Diabetes Mellitus. American journal of obstetrics and gynecology, 217(3).