The US Preventive Services Task Force (USPSTF) grades its recommendations (A, B, C, D, or I) and identifies the Levels of Certainty regarding Net Benefit (High, Moderate, and Low). The definitions of these grades can be found at the end of the "Major Recommendations" field.
Summary of Recommendations and Evidence
The USPSTF concludes that the current evidence is insufficient to assess the balance of benefits and harms of screening for gestational diabetes mellitus (GDM), either before or after 24 weeks gestation. This is an I statement.
Clinical Considerations
Patient Population Under Consideration
This recommendation concerns pregnant women who have not previously been diagnosed with diabetes.
Suggestions for Practice Regarding the I Statement
Until there is better evidence, clinicians should discuss screening for GDM with their patients and make case-by-case decisions. Discussions should include information about the uncertainty of benefits and harms as well as the frequency of positive screening test results.
Assessment of Risk
Women who are obese, older than 25 years of age, have a family history of diabetes, have a history of previous GDM, or are of certain ethnic groups (Hispanic, American Indian, Asian, or African-American) are at increased risk of developing GDM.
Screening Tests
In the United States, the most common screening test is an initial 50-gram 1-hour glucose challenge test (GCT). If the result of the GCT is abnormal, variably defined as either greater than 130 mg/dL or 140 mg/dL, the patient undergoes a 100-gram 3-hour oral glucose tolerance test (OGTT). Two or more abnormal values on the OGTT are considered a diagnosis of GDM.
Time of Screening
Most screening is conducted between 24 and 28 weeks gestation. There is little evidence about the value of earlier screening.
Treatment
Treatment usually includes recommendations for physical activity and dietary modification. In addition, treatment sometimes includes medication (either insulin or oral hypoglycemic agents), support from diabetes educators and nutritionists, and increased surveillance in prenatal care. The extent to which these interventions improve health outcomes is uncertain.
Other Approaches to Prevention
Nearly all pregnant women should be encouraged to achieve moderate weight gain based on their pre-pregnancy body mass index (BMI) and to participate in physical activity.
Definitions:
What the United States Preventive Services Task Force (USPSTF) Grades Mean and Suggestions for Practice
| Grade |
Grade Definitions |
Suggestions for Practice |
| A |
The USPSTF recommends the service. There is high certainty that the net benefit is substantial. |
Offer or provide this service. |
| B |
The USPSTF recommends the service. There is high certainty that the net benefit is moderate or there is moderate certainty that the net benefit is moderate to substantial. |
Offer or provide this service. |
| C |
The USPSTF recommends against routinely providing the service. There may be considerations that support providing the service in an individual patient. There is moderate or high certainty that the net benefit is small. |
Offer/provide this service only if there are other considerations in support of the offering/providing the service in an individual patient. |
| D |
The USPSTF recommends against the service. There is moderate or high certainty that the service has no net benefit or that the harms outweigh the benefits. |
Discourage the use of this service. |
I
Statement
|
The USPSTF concludes that the current evidence is insufficient to assess the balance of benefits and harms of the service. Evidence is lacking, of poor quality or conflicting, and the balance of benefits and harms cannot be determined. |
Read "Clinical Considerations" section of USPSTF Recommendation Statement (see "Major Recommendations" field). If offered, patients should understand the uncertainty about the balance of benefits and harms. |
USPSTF Levels of Certainty Regarding Net Benefit
Definition: The U.S. Preventive Services Task Force defines certainty as "likelihood that the USPSTF assessment of the net benefit of a preventive service is correct." The net benefit is defined as benefit minus harm of the preventive service as implemented in a general, primary care population. The USPSTF assigns a certainty level based on the nature of the overall evidence available to assess the net benefit of a preventive service.
| Level of Certainty |
Description |
| High |
The available evidence usually includes consistent results from well-designed, well-conducted studies in representative primary care populations. These studies assess the effects of the preventive service on health outcomes. This conclusion is therefore unlikely to be strongly affected by the results of future studies. |
| Moderate |
The available evidence is sufficient to determine the effects of the preventive service on health outcomes, but confidence in the estimate is constrained by factors such as:
- The number, size, or quality of individual studies
- Inconsistency of findings across individual studies
- Limited generalizability of findings to routine primary care practice
- Lack of coherence in the chain of evidence
As more information becomes available, the magnitude or direction of the observed effect could change, and this change may be large enough to alter the conclusion.
|
| Low |
The available evidence is insufficient to assess effects on health outcomes. Evidence is insufficient because of:
- The limited number or size of studies
- Important flaws in study design or methods
- Inconsistency of findings across individual studies
- Gaps in the chain of evidence
- Findings not generalizable to routine primary care practice
- A lack of information on important health outcomes
More information may allow an estimation of effects on health outcomes.
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