Gestational diabetes mellitus (GDM) is
defined as glucose intolerance of variable degree with onset or first
recognition during pregnancy. A study by Stuebe et al found this condition to
be associated with persistent metabolic dysfunction in women at 3 years after
delivery, separate from other clinical risk factors.
Infants of mothers with
preexisting diabetes mellitus experience double the risk of serious injury at
birth, triple the likelihood of cesarean delivery, and quadruple the incidence
of newborn intensive care unit (NICU) admission.
Gestational diabetes mellitus
accounts for 90% of cases of diabetes mellitus in pregnancy, while preexisting
type 2 diabetes accounts for 8% of such cases.
Screening for
diabetes mellitus during pregnancy
The following 2-step screening system for
gestational diabetes is currently recommended in the United States:
·
50-g, 1-hour glucose challenge
test (GCT)
·
100-g, 3-hour oral glucose tolerance test (OGTT) -
For patients with an abnormal GCT result
Alternatively, for high-risk women or in areas in
which the prevalence of insulin resistance is 5% or higher (eg, the
southwestern and southeastern United States), a 1-step approach can be used by
proceeding directly to the 100-g, 3-hour OGTT.
The US Preventive Services Task Force (USPSTF)
recommends screening for gestational diabetes mellitus after 24 weeks of
pregnancy. The recommendation applies to asymptomatic women with no previous
diagnosis of type 1 or type 2 diabetes mellitus. The
recommendation does not specify whether the 1-step or 2-step screening approach
would be preferable.
Type 1 diabetes
·
The disease is typically diagnosed during an
episode of hyperglycemia, ketosis, and dehydration
·
It is most commonly diagnosed in childhood or
adolescence; the disease is rarely diagnosed during pregnancy
·
Patients diagnosed during pregnancy most often
present with unexpected coma - Early pregnancy may provoke diet and glycemic
control instability in patients with occult diabetes
Type 2 diabetes
According to the American Diabetes Association’s
"Standards of Medical Care in Diabetes--2010," the
presence of any one of the following criteria supports the diagnosis of diabetes
mellitus:
· Haemoglobin A1C (HbA1C)
= 6.5%
·
Fasting plasma glucose = >126 mg/dL (7.0 mmol/L)
·
A 2-hour plasma glucose level = 200 mg/dL (11.1
mmol/L) during a 75-g OGTT
·
A random plasma glucose level = 200 mg/dL (11.1
mmol/l) in a patient with classic symptoms of hyperglycemia or hyperglycemic
crisis
Management
Diet
The goal of dietary therapy
is to avoid single large meals and foods with a large percentage of simple
carbohydrates. The diet should include foods with complex carbohydrates and
cellulose, such as whole grain breads and legumes.
Insulin
The goal of insulin therapy
during pregnancy is to achieve glucose profiles similar to those of nondiabetic
pregnant women. In gestational diabetes, early intervention with insulin or an
oral agent is key to achieving a good outcome when diet therapy fails to
provide adequate glycemic control.
Glyburide and metformin
The efficacy and safety of
insulin have made it the standard for treatment of diabetes during pregnancy.
Diabetic therapy with the oral agents glyburide and metformin, however, has
been gaining in popularity. Trials have shown these 2 drugs to be effective,
and no evidence of harm to the fetus has been found, although the potential for
long-term adverse effects remains a concern.
Prenatal obstetric management
Various fetal biophysical tests can ensure that the fetus is
well oxygenated, including fetal heart rate testing, fetal movement assessment,
ultrasonographic biophysical scoring, and fetal umbilical Doppler
ultrasonographic studies.
Management of the neonate
Current recommendations for
infants of diabetic mothers—the most critical metabolic problem for whom is
hypoglycemia—include the employment of frequent blood glucose checks and early
oral feeding (ideally from the breast) when possible, with infusion of
intravenous glucose if oral measures prove insufficient.
