Gestational Diabetes Mellitus (GDM)

Gestational diabetes Mellitus (GDM) is a condition characterized by high blood sugar (glucose) levels that is first recognized during pregnancy. It may also be called glucose intolerance or carbohydrate intolerance. Diabetes means that your blood glucose is too high. Your body uses glucose for energy. But too much glucose in your blood can be harmful. 

Risk Factors: You are at greater risk for gestational diabetes if you:

• Were overweight prior to becoming pregnant
• Are older than 30 when you are pregnant
• Have a family history of diabetes
• Having gestational diabetes with a previous pregnancy
• Having too much amniotic fluid (a condition called polyhydramnios)
• Gave birth to a baby that weighed more than 4 kg or had a birth defect
• Have had an unexplained miscarriage or stillbirth
• Have high blood pressure

Symptoms: Usually there are no symptoms, or the symptoms are mild and not life threatening to the pregnant woman. The blood glucose level usually returns to normal after delivery. Symptoms may include:

• Increased thirst.
• Increased urination.
• Increased hunger.
• Weight loss despite increased appetite.
• Blurred vision.

Investigation: High risk women should be screened for gestational diabetes as early as possible during their pregnancies. All other women will be screened between the 24th and 28th week of pregnancy.

Currently, the diagnostic test for GDM recommended by the Diabetes in Pregnancy Study Group of India (DIPSI) is an evaluation of plasma glucose after two hours of ingestion of 75 gm glucose load irrespective of meal timings. GDM is diagnosed if 2 hr plasma glucose is ≥140 mg/dl.

                  DIPSI Criteria for diagnosis of GDM (75 gm OGTT).

Criteria	In Pregnancy	Outside Pregnancy
2 hours  ≥ 200 mg/dl	Diabetes Mellitus	Diabetes Mellitus
2 hours  ≥ 140 mg/dl	GDM	Impaired glucose tolerance
2 hours  ≥ 120 mg/dl	Decreased gestational glucose tolerance

The American Diabetes Association (ADA) had recommended a 2-step approach to identify GDM with an initial Glucose Challenge Test (GCT), one-hour after 50 gm glucose load, irrespective of meal timings followed by a diagnostic 3-hours Oral Glucose Tolerance Test (OGTT) with 100 or 75 gm glucose load. GDM is diagnosed if any 2 values meet or exceed fasting plasma glucose > 95 mg/dl, one-hour > 180 mg/dl, two-hour > 155 mg/dl and three-hour > 140 mg/dl.

According to the World Health Organization (WHO) criteria, GDM is diagnosed using 75 g OGTT with fasting plasma glucose value >126 mg/dl or two-hour >140 mg/dl, 

The International Association of Diabetes and Pregnancy Study Groups (IADPSG) recommended a single-step approach to the diagnosis of GDM in 2010. They recommended 75 gm OGTT for all pregnant women and diagnosed GDM if one or more plasma venous glucose values exceeded the following thresholds: fasting >92 mg/dl, one hour ≥180.0 mg/dl, or two hour ≥153 mg/dl. The WHO (2013) and ADA (2014) have accepted the IADPSG criteria. 

Management: The goals of treatment are to keep blood sugar (glucose) levels within normal limits during the pregnancy, and to make sure that the growing baby is healthy. Intensive monitoring, diet and insulin is the corner stone of GDM management. You will talk with a dietitian or a diabetes educator who will design a meal plan to help you choose foods that are healthy for you and your baby. Physical activity, such as walking and swimming, can help you reach your blood glucose targets. Some women with gestational diabetes need insulin, in addition to a meal plan and physical activity, to reach their blood glucose targets.

References: 

10.4103/ijmr.IJMR_1716_15

10.7860/JCDR/2016/17588.7689