GDM: Self-monitoring of Glucose (2001)
Aberg A, Rydhstroem H, Frid A. Impaired glucose tolerance associated with adverse pregnancy outcome: A population-based study in southern Sweden. Am J Obstet Gynecol 2000;184:77-83.

- Singleton pregnancy
- Delivery at Lund Hospital
- Delivery <25 wk gestation
- Insulin dependent diabetes upon entry into study
- Diagnosis of GDM before 25 wk gestation
Recruitment
January 1, 1995 to December 31, 1997 OGTT’s were performed on all pregnant women between 27 and 28 wk gestation in 4 geographic areas of southern Sweden.
Prenatal care is free in Sweden and all women in Sweden have screening for diabetes at 25-30 wk gestation.
Design: Population-Based Descriptive Study
Blinding Used (if applicable): not applicable
Intervention (if applicable):
- All received device for home glucose monitoring.
- Blood glucose was tested 6 times/d if on insulin and 6 times every other day if not on insulin.
- A diabetologist called every woman with GDM every wk or every other wk
Statistical Analysis
Statistical analysis was performed with the Mantel-Haenszel method after various stratifications. Each group was compared with all other groups. 95% confidence intervals were determined by test-based method.
Timing of Measurements
75 g, 2 hour oral glucose tolerance test at 25 to 30 weeks gestation.
Dependent Variables
- Method of delivery
- Gestational age at delivery
- Birth weight
Independent Variables
- 75 g, 2 hour oral glucose tolerance test at 25 to 30 weeks gestation:
- Overnight fasting
- 75 g glucose given, followed by a 2-hr whole blood glucose determination
Blood glucose at 2-hr:
- Gestational diabetes: >9 mmol/L (162 mg/dl)
- Sub-GDM group: 7.8 to 8.9 mmol/L (140-162 mg/dl)
- Control group: <7.8 mmol/L (140 mg/dl)
Control Variables
- Age
- Parity
- Smoking habits
Initial N: 20,865 deliveries in 4 hospitals
Attrition (final N): as above
Age: mean age not provided, all subjects stratified for age
Ethnicity: not mentioned
Other relevant demographics:
Anthropometrics:
Location: Southern Sweden
Other Findings
20,865 deliveries in 4 hospitals
- 14,078 women had OGTT (67% coverage)
- 12,657 (93%) had OGTT 25-30 wk gestation.
- 4526 women with OGTT <7.8 mmol/L
- 131 women with OGTT: 7.8 to 8.9 mmol/L
- 116 women with GDM: >9 mmol/L
- (1.2% had GDM)
Odds ratio for having sub-GDM in 26-28.9 BMI group 1.13 (95%, CI 0.75-1.71).
Odds ratio for having GDM with BMI 26-28.9: 2.39 (95% CI, 1.39-4.10) and for GDM with BMI >29: 3.88 (95% CI, 2.37-6.36).
40% of women treated with insulin
Sub-GDM | GDM | Control | |
% | |||
C-Section | 13.8 | 18.1 | 7.8 |
<37 wk at delivery |
8.4 | 13.8 | 5.7 |
(P<0.001 for trend) |
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Birthweight >4500 g |
9.9 | 10.3 | 4.5 |
(P<0.001 for trend) |
We conclude that women with a 2-hr oral GTT of 7.8 to 8.9 mmol/L have an increased risk of having a nonoptimal delivery outcome.
Women with GDM, despite having an increased BMI, were delivered of normal-size babies probably due to the intense treatment given.
Good population study because all women in Sweden receive prenatal care and all women are screened for GDM at 25-30 wk gestation.
Quality Criteria Checklist: Primary Research
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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? | N/A | |
3.1. | Was the method of assigning subjects/patients to groups described and unbiased? (Method of randomization identified if RCT) | N/A | |
3.2. | Were distribution of disease status, prognostic factors, and other factors (e.g., demographics) similar across study groups at baseline? | N/A | |
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? | N/A | |
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? | N/A | |
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? | N/A | |
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? | N/A | |
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? | 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 | |