GDM: Physical Activity (2008)

Citation:
 
Study Design:
Class:
- Click here for explanation of classification scheme.
Quality Rating:
Research Purpose:
A forum for the review of new information concerning GDM in the areas of diagnosis and prevalence, perinatal and long-range implications for the mother and her offspring.
Inclusion Criteria:
Not described.
Exclusion Criteria:
Not described.
Description of Study Protocol:

Recruitment:  Not applicable

Design:  Summary and Recommendations of Workshop.

Blinding used (if applicable):  Not applicable

Intervention (if applicable):  Not applicable

Statistical Analysis:  None reported.

 

Data Collection Summary:

Timing of Measurements:  Not stated.

Dependent Variables:  Not available. 

Independent Variables: Not available.

Control Variables:  Not available.

 

Description of Actual Data Sample:

Initial N: 8 references

Attrition (final N):

Age: Not available.

Ethnicity: Not available.

Other relevant demographics: Not available.

Anthropometrics Not available.

Location: Not available.

 

Summary of Results:

Definition of GDM:  Carbohydrate intolerance of varying degrees of severity, with onset or first recognition during pregnancy.

Diagnosis and Prevalence - 

Screening Strategy for detecting GDM

Risk assessment should be ascertained at first prenatal visit.

Low risk if all the following are met and blood test not routinely required:

  • Member of an ethnic group with a low prevalence of GDM
  • No known diabetes in first degree relatives
  • Age less than 25 years
  • Weight normal before pregnancy
  • No history of abnormal glucose metabolism
  • No history of poor obstetric outcome

Average risk

  • Perform BG test at 24-28 weeks using one of the following:
  • 2 step procedure: 50 g GCT followed by a diagnostic OGTT in those meeting the threshold value in the GCT
  • 1 step procedure: diagnostic OGTT performed on all subjects

High risk

  • Perform blood glucose testing as soon as feasbile using the procedures described above.  If GDM is not diagnosed, blood glucose testing should be repeated at 24-28 weeks or at any time a patient has symptoms or signs suggestive of hyperglycemia.

Additional information related to diagnosis and prevalence:

  • The cutoff values for the 100g GTT diagnostic test designate a population at increased risk for perinatal morbidity as well as the development of type 2 diabetes later in life.  
  • Cuf-off values for the 75 g 2h OGTT in pregnancy are arbitrary.  It is recommended that appropriately designed clinical trials be conducted to determine if the results of the 75 g test can be applied in a similar fashion. 

Cut off values for both 100 g GTT and 75 g GTT

  100 g GTT 75 g GTT
Fasting 95 95
1 h 180 180
2 h 155 155
3 h 140 --

Perinatal Implications -

  • More widespread testing and identification of GDM as well as intensive management appear to be associated with a decrease in overall morbidity in infants of mothers with GDM.
  • The primary perinatal concern in GDM remains excessive fetal growth.
  • The use of ultrasonography to estimate fetal size and to detect asymmetric fetal growth may improve our ability to direct costly and labor-intensive maternal therapy at high-risk pregnancy.
  • The cesarean delivery rate is increased in patients with GDM, in part to avoid birth trauma, despite the controversy related to the need for cesarean delivery.
  • Although a precise definition of neonatal hypoglycemia is not universally accepted, development of neonatal hypoglycemia should be confirmed by accurate laboratory measurement of plasma glucose and not made solely with the use of glucose reagent strips and meter.

Therapeutic Interventions during Pregnancy -

  • There is a need to develop strategies combining fetal measurements with monitoring of maternal glycemia to distinguish low-risk from high-risk pregnancies.
  • While MNT is the cornerstone for GDM treatment, there is little information to allow evidence based recommendations regarding specific dietary approaches to the management of GDM.  MNT should be used to achieve glycemic controls, but should be individualized to the patient and should not induce excessive ketonemia and ketonuria.
  • BG self-monitoring is superior to less frequent glucose monitoring in clinics.
  • Urine glucose monitoring is not useful in the management of GDM.
  • Postprandial levels may be more closely related to fetal risks than are fasting levels.  Hence BG monitoring should include post meal testing.
  • Patients who fail to meet glycemic control through diet, should be placed on insulin.  No one insulin regimen has been shown to be superior.
  • Exercise may be used as an adjunct to MNT to aid with glycemic control.  Exercising a minimum of 3x/week for greater than 15 minutes is needed to aid with improved glycemic control.
  • Maternal hyperglycemia during labor should be avoided because it may potentiate the risk of neonatal hypoglycemia and accentuate the rise in lactate and decline in pH that normally accompany any fetal hypoxia.  It is recommended that BG levels be monitored at 1 to 4 hour intervals from the onset of spontaneous or induced labor and that insulin be administered only if maternal glycemia exceeds the target range.
  • At a minimum, mothers with GDM should be taught to monitor fetal movements during the last 8-10 weeks of pregnancy and to report immediately any reduction in the perception of fetal movements. 
  • The use of ultrasound to measure the fetal abdominal circumference at 29-33 weeks' gestation was demonstrated to be useful for identifying a large subset of patients with maternal fasting glucose levels <105 mg/dl who were at little risk for fetal macrosomia at term when managed with dietary therapy alone.
  • Amniocentesis for assessment of fetal lung maturity was not felt to be indicated in well-controlled patients after 38 weeks' gestation as long as there is reasonable certainty about the estimation of gestational age.  Use of amniocentesis before 38 weeks' gestation should be guided by the indications for preterm delivery.
  • Measurement of blood pressure, body weight and urinary protein was recommended at each prenatal visit to detect the development of pregnancy-induced hypertension.
  • There was consensus that the presence of GDM should not of itself constitute an indication for elective cesarean delivery.  It would be reasonable to intensify fetal surveillance when pregnancy is allowed to continue beyond 40 weeks' gestation.

Long-range implications and management after pregnancy -

The mother

  • GDM is associated with a high lifetime risk for diabetes in the mother, although most women with GDM return to normal glucose tolerance postpartum.  Generally this is type 2, but type 1 can occur and is related to ethnicity.
  • Certain drugs including corticosteroids, nicotinamide and high dose thiazide diuretics may affect glucose metabolism adversely, and if clinically indicated should be used with care in women with prior GDM.
  • Data reviewed suggested that low-dose estrogen and progestin contraceptives may be used safely in women with previous GDM, whereas progestin-only contraceptives may increase the short-term risk of diabetes.  Studies of long duration, however, are not available.
  • Health care providers should counsel women concerning risks of glucose intolerance and future diabetes by making them aware of the symptoms of diabetes and the need for regular postpartum surveillance, even in the absence of symptoms.
  • Glucose tolerance should be reevaluated in the mother initially at 6-12 weeks postpartum.  If the postpartum evaluation does not indicate diabetes, fasting plasma glucose concentrations should be assessed at least annually and in prepartion for any future pregnancy.
  • Because all subsequent pregnancies carry a risk for GDM or pre-GDM, all women with prior GDM need to participate in a program for planned pregnancies.

The offspring

  • By the time of puberty, the offspring of women with GDM have increased risk of obesity and abnormal glucose tolerance. 
  • Measures aimed at reducing or preventing obesity by modification of lifestyle may also decrease the risk of obesity and diabetes in the offspring.
  • Breastfeeding should be encouraged as it may be associated with a lower risk of obesity, and in some populations diabetes in the offspring.

 

Author Conclusion:

The diagnosis of GDM provides an important opportunity to identify women at high risk for future diabetes.  This opportunity should be used to develop intervention strategies that can be tested in clinical trials aimed at delaying or preventing the onset of diabetes and its long-term consequences.

More studies are needed during pregnancy, at birth, and during childhood and adolescence to further indentify those children most at risk for diabetes and obesity and to understand what contribution is made by maternal metabolic, intrauterine, genetic, lifestyle and other host risk factors to the lifetime susceptibility to obesity and diabetes.

Evidence that transmission of diabetes to subsequent generations may involve intrauterine exposures to hypergylcemia or to other nutrients and agents that may cause stimulation of fetal hyperinsulinism in addition to standard genetic transmission speaks strongly of the need for studies to define the mechanisms that may be involved.

Funding Source:
Reviewer Comments:

Very thorough summary of issues, discussions and recommendations of the Workshop.

Report recommendations can be used to help guide GDM care.

Quality Criteria Checklist: Review Articles
Relevance Questions
  1. Will the answer if true, have a direct bearing on the health of patients? Yes
  2. Is the outcome or topic something that patients/clients/population groups would care about? Yes
  3. Is the problem addressed in the review one that is relevant to dietetics practice? Yes
  4. Will the information, if true, require a change in practice? No
 
Validity Questions
  1. Was the question for the review clearly focused and appropriate? Yes
  2. Was the search strategy used to locate relevant studies comprehensive? Were the databases searched and the search termsused described? No
  3. Were explicit methods used to select studies to include in the review? Were inclusion/exclusion criteria specified andappropriate? Wereselectionmethods unbiased? No
  4. Was there an appraisal of the quality and validity of studies included in the review? Were appraisal methodsspecified,appropriate, andreproducible? No
  5. Were specific treatments/interventions/exposures described? Were treatments similar enough to be combined? Yes
  6. Was the outcome of interest clearly indicated? Were other potential harms and benefits considered? Yes
  7. Were processes for data abstraction, synthesis, and analysis described? Were they applied consistently acrossstudies and groups? Was thereappropriate use of qualitative and/or quantitative synthesis? Was variation in findings among studies analyzed? Were heterogeneity issued considered? If data from studies were aggregated for meta-analysis, was the procedure described? No
  8. Are the results clearly presented in narrative and/or quantitative terms? If summary statistics are used, are levels ofsignificance and/or confidence intervals included? Yes
  9. Are conclusions supported by results with biases and limitations taken into consideration? Are limitations ofthe review identified anddiscussed? Yes
  10. Was bias due to the review's funding or sponsorship unlikely? Yes