GDM: Pharmacologic Therapy (2008)

Citation:
 
Study Design:
Class:
- Click here for explanation of classification scheme.
Quality Rating:
Research Purpose:
The purpose of this study was to determine the comparison of glyburide and insulin in women with gestational diabetes mellitus (GDM) with regards to glycemic control and the incidence of maternal and neonatal complications.
Inclusion Criteria:
  • Women with GDM (fasting plasma glucose levels of >  95 mg/dl and < 140 mg/dl at the time of oral glucose-tolerance testing) and at 11-33 weeks gestation.
  • Women with fasting plasma glucose (FPG) levels < 95 mg/dl were enrolled in the study if after being treated with diet only their FPG levels were 95 mg/dl or their postprandial plasma glucose concentrations were > 120 mg/dl.
  • Singleton pregnancies only
Exclusion Criteria:
Excluded if not included above.
Description of Study Protocol:

Recruitment

Women were recruited from maternal health clinics in San Antonio Texas.

Design

All subjects were instructed in standard nutritional recommendations for GDM. Diet prescriptions were designed to provide 25 kcal/kg body weight for obese women and 35 kcal/kg body weight for the nonobese.

Women were randomly assigned to either receive glyburide or insulin and monitored through out their pregnancy. Neonates were assessed at birth.

Blinding used (if applicable)

None

Intervention (if applicable)

The glyburide group received glyburide at 2.5 mg orally initially and increased as indicated the following week by 2.5 mg and thereafter by 5 mg weekly to a total of 20 mg to achieve glycemic control.

Women who were assigned insulin were given 0.7 u per kg actual body weight at admission, given subcutaneously three times daily and increased weekly as necessary.

Statistical Analysis

Chi-square tests were used to compare categorical data between the two treatment groups and student's t tests were used to compare numerical data.

 

Data Collection Summary:

Timing of Measurements

Women were instructed to measure blood glucose 7 times daily (upon fasting, before and 2 hours after each meal and at bedtime).

Neonatal assessment was done at delivery and glucose was measured from heel blood at least 3 times during the first hour after birth and every 30 minutes up to hour 4.

Dependent Variables

  • Maternal glycemic control 
  • Neonatal outcomes (birth weight, blood glucose levels)

Independent Variables

  • Glyburide versus insulin therapy

Control Variables

None 

Description of Actual Data Sample:

Initial N: 404 women (201 glyburide group, 203 insulin group)

Attrition (final N): 404

Age: ranged from 18- 40 years

Ethnicity: 83% were Hispanic (mostly Mexican-American), 12% were non-Hispanic whites and 5% were black

Other relevant demographics: all were Medicaid recipients, majority had completed 10th grade

Anthropometrics

There were no signficant differences between groups in age, pre-pregnancy BMI, results of OGTT or previous delivery of infant with macrosomia, or hemoglobin AIC values before treatment.

Location:

San Antonio Texas

 

Summary of Results:

 

Maternal characteristics

Glyburide group

Insulin group

P values

Week of gestation when blood glucose testing started (mean + SD)

28 + 6

27 + 8

0.22

Blood glucose mg/dl mean (mean +  SD)

 105 + 16

 

 105 + 18

 0.99

Glycosylated hemoglobin (%)

 5.5  +0.7

 5.4 + 0.6

 0.12

 

Neonatal outcomes

Glyburide group

Insulin group

P values

Large for gestational age - no (%) 24 (12)

26 (13)

0.76

Birth weight (g + SD)

 3256 + 543 

 3194+  598

 0.28

Macrosomia  - no (%)

  14 (7)

 9 (4)

 0.26

Congenital anomaly - no (%) 5 (2) 4 (2) 0.74
Admission to NICU - no (%) 12 (6) 14 (7) 0.68

Other Findings

There were no signficant differences in degree of glycemic control, rate of cesarean section or the rate of preeclampsia after stratification according to gestational age.

 

Author Conclusion:

In women with gestational diabetes, glyburide is a clinically effective alternative to insulin therapy.

Funding Source:
University/Hospital: St. Luke's Roosevelt, University of Texas Health Science Center
Reviewer Comments:
Quality Criteria Checklist: Primary Research
Relevance Questions
  1. Would implementing the studied intervention or procedure (if found successful) result in improved outcomes for the patients/clients/population group? (Not Applicable for some epidemiological studies) Yes
  2. Did the authors study an outcome (dependent variable) or topic that the patients/clients/population group would care about? Yes
  3. Is the focus of the intervention or procedure (independent variable) or topic of study a common issue of concern to dieteticspractice? Yes
  4. Is the intervention or procedure feasible? (NA for some epidemiological studies) Yes
 
Validity Questions
1. Was the research question clearly stated? Yes
  1.1. Was (were) the specific intervention(s) or procedure(s) [independent variable(s)] identified? Yes
  1.2. Was (were) the outcome(s) [dependent variable(s)] clearly indicated? Yes
  1.3. Were the target population and setting specified? Yes
2. Was the selection of study subjects/patients free from bias? Yes
  2.1. Were inclusion/exclusion criteria specified (e.g., risk, point in disease progression, diagnostic or prognosis criteria), and with sufficient detail and without omitting criteria critical to the study? Yes
  2.2. Were criteria applied equally to all study groups? Yes
  2.3. Were health, demographics, and other characteristics of subjects described? Yes
  2.4. Were the subjects/patients a representative sample of the relevant population? ???
3. Were study groups comparable? Yes
  3.1. Was the method of assigning subjects/patients to groups described and unbiased? (Method of randomization identified if RCT) Yes
  3.2. Were distribution of disease status, prognostic factors, and other factors (e.g., demographics) similar across study groups at baseline? Yes
  3.3. Were concurrent controls or comparisons used? (Concurrent preferred over historical control or comparison groups.) N/A
  3.4. If cohort study or cross-sectional study, were groups comparable on important confounding factors and/or were preexisting differences accounted for by using appropriate adjustments in statistical analysis? N/A
  3.5. If case control study, were potential confounding factors comparable for cases and controls? (If case series or trial with subjects serving as own control, this criterion is not applicable.) N/A
  3.6. If diagnostic test, was there an independent blind comparison with an appropriate reference standard (e.g., "gold standard")? N/A
4. Was method of handling withdrawals described? Yes
  4.1. Were follow-up methods described and the same for all groups? Yes
  4.2. Was the number, characteristics of withdrawals (i.e., dropouts, lost to follow up, attrition rate) and/or response rate (cross-sectional studies) described for each group? (Follow up goal for a strong study is 80%.) Yes
  4.3. Were all enrolled subjects/patients (in the original sample) accounted for? Yes
  4.4. Were reasons for withdrawals similar across groups? Yes
  4.5. If diagnostic test, was decision to perform reference test not dependent on results of test under study? N/A
5. Was blinding used to prevent introduction of bias? Yes
  5.1. In intervention study, were subjects, clinicians/practitioners, and investigators blinded to treatment group, as appropriate? Yes
  5.2. Were data collectors blinded for outcomes assessment? (If outcome is measured using an objective test, such as a lab value, this criterion is assumed to be met.) Yes
  5.3. In cohort study or cross-sectional study, were measurements of outcomes and risk factors blinded? N/A
  5.4. In case control study, was case definition explicit and case ascertainment not influenced by exposure status? N/A
  5.5. In diagnostic study, were test results blinded to patient history and other test results? N/A
6. Were intervention/therapeutic regimens/exposure factor or procedure and any comparison(s) described in detail? Were interveningfactors described? Yes
  6.1. In RCT or other intervention trial, were protocols described for all regimens studied? Yes
  6.2. In observational study, were interventions, study settings, and clinicians/provider described? N/A
  6.3. Was the intensity and duration of the intervention or exposure factor sufficient to produce a meaningful effect? Yes
  6.4. Was the amount of exposure and, if relevant, subject/patient compliance measured? Yes
  6.5. Were co-interventions (e.g., ancillary treatments, other therapies) described? No
  6.6. Were extra or unplanned treatments described? ???
  6.7. Was the information for 6.4, 6.5, and 6.6 assessed the same way for all groups? Yes
  6.8. In diagnostic study, were details of test administration and replication sufficient? N/A
7. Were outcomes clearly defined and the measurements valid and reliable? Yes
  7.1. Were primary and secondary endpoints described and relevant to the question? Yes
  7.2. Were nutrition measures appropriate to question and outcomes of concern? Yes
  7.3. Was the period of follow-up long enough for important outcome(s) to occur? Yes
  7.4. Were the observations and measurements based on standard, valid, and reliable data collection instruments/tests/procedures? Yes
  7.5. Was the measurement of effect at an appropriate level of precision? Yes
  7.6. Were other factors accounted for (measured) that could affect outcomes? Yes
  7.7. Were the measurements conducted consistently across groups? Yes
8. Was the statistical analysis appropriate for the study design and type of outcome indicators? Yes
  8.1. Were statistical analyses adequately described and the results reported appropriately? Yes
  8.2. Were correct statistical tests used and assumptions of test not violated? Yes
  8.3. Were statistics reported with levels of significance and/or confidence intervals? Yes
  8.4. Was "intent to treat" analysis of outcomes done (and as appropriate, was there an analysis of outcomes for those maximally exposed or a dose-response analysis)? Yes
  8.5. Were adequate adjustments made for effects of confounding factors that might have affected the outcomes (e.g., multivariate analyses)? Yes
  8.6. Was clinical significance as well as statistical significance reported? Yes
  8.7. If negative findings, was a power calculation reported to address type 2 error? N/A
9. Are conclusions supported by results with biases and limitations taken into consideration? Yes
  9.1. Is there a discussion of findings? Yes
  9.2. Are biases and study limitations identified and discussed? Yes
10. Is bias due to study's funding or sponsorship unlikely? Yes
  10.1. Were sources of funding and investigators' affiliations described? Yes
  10.2. Was the study free from apparent conflict of interest? Yes