EAL

GDM: Monitoring (2008)

Citation:

Study Design:

Class:

- Click here for explanation of classification scheme.

Quality Rating:

Research Purpose:

To compare the rate of adverse perinatal outcomes among women with gestational diabetes mellitus, monitored by 1 versus 2 hour postprandial glucose measurements.

Inclusion Criteria:

Women diagnosed with GDM according to criteria of Carpenter and Coustan

Exclusion Criteria:

Women with pregestational diabetes or fasting glucose levels of 105 mg/dl and above due to initiation of insulin treatment
Twin pregnancies

Description of Study Protocol:

Recruitment

Consecutive pregnancies referred to diabetes-in-pregnancy program between May 1999 and April 2000. Women were recruited from 2 different treatment settings but were managed by the same team of health care professionals using a standardized protocol.

Design: Nonrandomized Clinical Trial. Allocation to treatment group was based on treatment setting.

Blinding used (if applicable): not possible

Intervention (if applicable)

Assigned to 1 hour or 2 hour monitoring groups
Glucose levels measured fasting, and either 1 hour (1-hour monitoring group target values <140 mg/dl) or 2 hours (2-hour monitoring group target values <120 mg/dl) postprandially
All women seen by registered dietitian for individualized counseling and instruction
All women given a memory-based blood glucose meter
Insulin therapy initiated on individual basis

Statistical Analysis

Statistical analysis performed using Student's t test, chi-square test, and multiple regressions.

Data Collection Summary:

Timing of Measurements

Measurements completed during pregnancy.

Dependent Variables

Perinatal outcomes collected from medical records: gestational week at delivery, fetal weight, weight percentile at delivery, rate of macrosomia (>4000 g) and large for gestational age (LGA > 90th percentile)

Independent Variables

Glucose levels measured fasting, and either 1 hour (1-hour monitoring group target values <140 mg/dl) or 2 hours (2-hour monitoring group target values <120 mg/dl) postprandially

Control Variables

Demographic data

Description of Actual Data Sample:

Initial N: 122 women with GDM

Attrition (final N): 112 women with GDM, 66 assigned to 1 hour monitoring group, 46 women to 2 hour monitoring group. 4 women excluded for twins, 6 women lost to follow up.

Age: mean age 1-hour monitoring: 30.9 ± 5.44 years, 2-hour monitoring: 33.1 ± 5.24 years

Ethnicity: not mentioned

Other relevant demographics:

Anthropometrics: Women in the 2 hour group were older, but there were no significant differences in parity, family history of diabetes, rate of GDM in previous pregnancies, weight gain, pregestational BMI and 50 g glucose challenge test and 100 g oral glucose challenge test results.

Location: Israel

Summary of Results:

Neonatal Outcomes by Treatment Group

	1-hour monitoring group (1 h PPG)	2-hour monitoring group (2 h PPG)	P value
Week at delivery	39.5 ± 1.7	39.1 ± 1.4	0.17
Fetal weight	3325 ± 471	3309 ± 608	0.88
Insulin therapy	40%	28%	0.03
Macrosomia	7.5%	10.6%	0.08
Cesarean section	24%	30%	0.62

Other Findings

There was a significant difference in mean blood glucose levels between the 2 groups (108.1 ± 19.2 and 94.9 ± 21.2 mg/dl, 1 and 2 hours respectively, P < 0.0001).

HbA1c levels were similar in the 2 groups.

Perinatal outcomes were defined as gestational week at delivery, fetal weight (3325 ± 471 vs 3309 ± 608 g, respectively) and percentile (47.2 ± 27 vs 49.6 ± 30, respectively) and were similar for both groups.

Insulin therapy was initiated more frequently in 2-hour monitoring group (28 and 40% of women in groups 1 and 2, respectively, P < 0.05).

Rates of macrosomia (7.5 vs 10.6%), large for gestational age (7.4 vs 15.2%) and delivery by Cesarean section (24 vs 30%) were increased in group 2 (2 hour PPG) but these differences did not reach statistical significance.

Neonatal birth weight was significantly correlated with maternal weight gain during pregnancy (P = 0.001) and a family history of diabetes (P = 0.02).

Author Conclusion:

These data suggest that diet control in women with GDM managed by 1-hour PPG measurements is associated with a decreased rate of insulin therapy. However, neonatal and obstetrical outcomes are not determined by the timing of their glucose determinations.

Funding Source:

Reviewer Comments:

Significant differences between treatment groups. Authors note that sample sizes were too small to assess less common perinatal complications.

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?	Yes
3.	Were study groups comparable?		No
	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?	No
	3.3.	Were concurrent controls or comparisons used? (Concurrent preferred over historical control or comparison groups.)	Yes
	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?	No
	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?	Yes
	6.6.	Were extra or unplanned treatments described?	Yes
	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)?	N/A
	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?	No
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