gestational
diabetes mellitusgestational diabetes mellitus
Definition : gestational diabetes mellitus
(GDM) is defined as any degree of glucose intolerance with onset or first recognition during pregnancy. The prevalence may range from 1 to 14% of all pregnancies,
Detection and diagnosis : patients with high risk of GDM (marked obesity, personal history of GDM, glycosuria, or a strong family history of
diabetes) should undergo glucose testing as soon as feasible. If they are found not to have GDM at that initial screening, they should be retested between 24 and 28 weeks of gestation. Women of average risk should have testing undertaken at 24–28 weeks of gestation.
A fasting plasma glucose level >126 mg/dl ( 7.0 mmol/l) or a casual plasma glucose >200 mg/dl (11.1 mmol/l) meets the threshold for the diagnosis of diabetes, if confirmed on a subsequent day, it precludes the need for any glucose challenge. In the absence of this degree of hyperglycemia, evaluation for GDM in women with average or high-risk characteristics should follow one of two approaches:
One-step approach : Perform a diagnostic oral glucose tolerance test (OGTT) without prior plasma or serum glucose screening. may be cost-effective
Two-step approach: initial screening by measuring the plasma or serum glucose concentration 1 h after a 50-g oral glucose load (glucose challenge test
) and perform a diagnostic OGTT on that subset of women exceeding the glucose threshold value on the GCT. a glucose threshold value >140 mg/dl (7.8 mmol/l) identifies approximately 80% of women with GDM
THERAPEUTIC STRATEGIES DURING PREGNANCY
Monitoring
. Daily self-monitoring of blood glucose (SMBG) appears to be superior to intermittent office monitoring. For women treated with insulin, limited evidence indicates that postprandial monitoring is superior to preprandial monitoring
Urine glucose monitoring is not useful in GDM. Urine ketone monitoring may be useful in detecting insufficient carbohydrate intake
blood pressure and urine protein monitoring to detect hypertensive disorders.
Increased surveillance for pregnancies at risk for fetal demise is appropriate, particularly when fasting glucose levels exceed 105 mg/dl (5.8 mmol/l) or pregnancy progresses past term.
Assessment for asymmetric fetal growth by ultrasonography, particularly in early third trimester, may aid in identifying fetuses that can benefit from maternal insulin therapy
. Management
All women with GDM should receive nutritional counseling, consistent with the recommendations by the American Diabetes Association. Individualization of medical nutrition therapy (MNT) depending on maternal weight and height is recommended.
For obese women (BMI >30 kg/m2), a 30–33% calorie restriction (to 25 kcal/kg actual weight per day) has been shown to reduce hyperglycemia and plasma triglycerides with no increase in ketonuria
insulin therapy is recommended when MNT fails to maintain self-monitored glucose at the following levels:
· Fasting whole blood glucose 95 mg/dl ( 5.3 mmol/l)
· Fasting plasma glucose 105 mg/dl (5.8 mmol/l) or
· 1-h postprandial whole blood glucose 140 mg/dl (7.8 mmol/l)
· 1-h postprandial plasma glucose 155 mg/dl (8.6 mmol/l) or
· 2-h postprandial whole blood glucose 120 mg/dl (6.7 mmol/l)
· 2-h postprandial plasma glucose 130 mg/dl (7.2 mmol/l)
Measurement of the fetal abdominal circumference early in the third trimester can identify macrosomia in the absence of maternal insulin therapy.
Human insulin should be used when insulin is prescribed, and SMBG should guide the doses and timing of the insulin regimen.
Oral glucose-lowering agents have generally not been recommended during pregnancy. Glyburide is not FDA approved for the treatment of GDM and further studies are needed in a larger patient population to establish its safety.
Programs of moderate physical exercise have been shown to lower maternal glucose concentrations in women with GDM. Although the impact of exercise on neonatal complications awaits rigorous clinical trials,
GDM is not of itself an indication for cesarean delivery or for delivery before 38 completed weeks of gestation. Prolongation of gestation past 38 weeks increases the risk of fetal macrosomia without reducing cesarean rates, so that delivery during the 38th week is recommended unless obstetric considerations dictate otherwise.
Breast-feeding, as always, should be encouraged in women with GDM.
LONG-TERM THERAPEUTIC CONSIDERATIONS
Reclassification of maternal glycemic status should be performed at least 6 weeks after delivery and according to the guidelines of the "Report of the Expert Committee on the Diagnosis and Classification of Diabetes Mellitus". If glucose levels are normal post-partum, reassessment of glycemia should be undertaken at a minimum of 3-year intervals. Women with IFG or IGT in the postpartum period should be tested for diabetes annually; these patients should receive intensive MNT and should be placed on an individualized exercise program because of their very high risk for development of diabetes. All patients with prior GDM should be educated regarding lifestyle modifications that lessen insulin resistance, including maintenance of normal body weight through MNT and physical activity. Medications that worsen insulin resistance (e.g., glucocorticoids, nicotinic acid) should be avoided if possible. Patients should be advised to seek medical attention if they develop symptoms suggestive of hyperglycemia. Education should also include the need for family planning to ensure optimal glycemic regulation from the start of any subsequent pregnancy. Low-dose estrogen-progestogen oral contraceptives may be used in women with prior histories of GDM, as long as no medical contraindications exist.
Offspring of women with GDM should be followed closely for the development of obesity and/or abnormalities of glucose tolerance.