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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.
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.
