ACOG issues clinical practice guidelines for Gestational Diabetes Mellitus

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The American College of Obstetricians and Gynecologists (ACOG) has issued clinical practice guidelines for the diagnosis and treatment of gestational diabetes mellitus (GDM).

Although prevalence of GDM is directly proportional to prevalence of type 2 DM in a given population, it is estimated that GDM accounts for 90% of cases diabetes in pregnancy. The prevalence of DM in pregnancy is around 6-9%.

The prevalence of GDM globally is on the rise because of increasing obesity, delayed childbearing and sedentary lifestyle.

The document provides a brief overview of GDM, one of the most common complication of pregnancy, identifies the disease process, its diagnosis and management based on current research and identifies the lacunae for future research.

Screening for GDM is done by various methods and there is still no standardized method. ACOG supports the two-step process most commonly used in USA. It involves first screening with the administration of a 50-g oral glucose solution followed by a 1-hour venous glucose determination. 

Women whose glucose levels meet or exceed an institution’s screening threshold then undergo a 100-g, 3-hour diagnostic OGTT. Gestational diabetes mellitus is most often diagnosed in women who have two or more abnormal values on the 3-hour OGTT.

Other institutions and private practitioners use International Association of Diabetes and Pregnancy Study Group (IADPSG) recommended one step, universal 75-g, 2-hour OGTT to diagnose GDM.

The summary of recommendations by ACOG:

Recommendations based on good scientific evidence (Level A):

All women diagnosed with GDM should first be treated with adequate nutritional and exercise counselling, before starting any pharmacological treatment.

If lifestyle modifications fail to control glucose levels, Insulin is the first line of drug for controlling blood sugar in pregnancy.

Recommendations based on limited or inconsistent scientific evidence (Level B):

All pregnant women should be screened for GDM with a laboratory based blood glucose level testing.

Women who refuse to take insulin, or who are unable to safely administer insulin, metformin is a reasonable second-line choice.

Glyburide is not be recommended as a first-line pharmacologic treatment because, in most studies, it does not yield equivalent outcomes to insulin.

All women should be counselled about limitations of safety data regarding oral hypoglycemic agents.

Women should also receive counselling regarding the risks and benefits of a scheduled cesarean delivery when the estimated fetal weight is 4,500 g or more.

Recommendations based primarily on consensus and expert opinion (Level C):

In the absence of clear evidence and comparative trials, no single value of blood glucose can be taken as cutoff over another for 1-hour glucose test nor one set of diagnostic criteria for the 3-hour OGTT can be clearly recommended over the other. Practitioners should select a single set of criteria and use it consistently with their patients.

Women should be advised dietary guidance and 30 minutes of moderate physical activity, 5 days a week or 150 minute/week.  

In women, whose GDM is well controlled by diet and exercise, delivery is not indicated before 39 weeks of gestation, in absence of other obstetric indication. She can be safely managed expectantly up to 40 6/7 weeks of gestation, with antepartum fetal surveillance.

In women, whose GDM is well controlled by medications, delivery is recommended at 39 0/7 to 39 6/7 weeks of gestation.

All women with GDM should be screened at 4–12 weeks postpartum to identify women with diabetes, impaired fasting glucose levels, or impaired glucose tolerance, with an appropriate referral to medical practitioner.

The American Diabetic Association (ADA) and ACOG recommend repeat testing every 1–3 years for women who had a pregnancy affected by GDM and normal postpartum screening test results.

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