GDM: Monitoring (2008)

Study Design:
- Click here for explanation of classification scheme.
Quality Rating:
Research Purpose:
To test the hypothesis that patient awareness of a memory function in a reflectance meter would improve the accuracy of reporting self-monitoring of blood glucose, regardless of patient ethnicity and geographic location.
Inclusion Criteria:
Pregnant women with gestational diabetes who received care in Bronx, New York and San Antonio, Texas.  
Exclusion Criteria:
None stated.
Description of Study Protocol:


Pregnant women with gestational diabetes who received care in Bronx, New York and San Antonio, Texas. Patients were admitted to the study on the basis of availability of reflectance meters.

Design:  Nonrandomized Clinical Trial 

Blinding used (if applicable):  None used 

Intervention (if applicable):

Women from both groups were trained and evaluated for blood glucose self-monitoring technique using a standard glucose meter. They were prospectively followed and their self-monitoring blood glucose performance was evaluated until delivery.

Statistical Analysis

  • T test was used to compare results of patient self-monitoring blood glucose between Groups 1 and 2
  • Univariate analysis was used to evaluate patient performance by race and location
Data Collection Summary:

Timing of Measurements

All subjects were directed to test their blood glucose 7 times/day (immediately before and 2 hours post-prandial and at bedtime and subjects were instructed to maintain logbooks of glucose values through out the study.  Random venous blood glucose samples were drawn on patients during routine clinic visits and values compared to simultaneous measurements on their glucometer.

Dependent Variables

  • Patient performance measured as: Precision (degree of concordance between the logbook and glucose meter readings), Overreporting error (degree to which the subject added   glucose values to the logbook) and Underreporting error (degree to which the subject omitted glucose value to the logbook)  
  • Patient compliance measured by:  Total number of daily glucose readings, weekly glucose readings,  Number of show/no show visits to diabetic clinic,  Percentage of glucose readings with values > 120 mg/DL 

Independent Variables

  • Geographic location
  • Ethnicity

Control Variables



Description of Actual Data Sample:

Initial N: 1102  (281 in Group 1, 821 in Group 2)

Attrition (final N): 1102

Age: Group 1:  30 + 5 years,  Group 2:  30 + 4 years

Ethnicity:  Group 1:  84 (30%) Hispanic, 133 (47%) African American, 64 (23%) White;  Group 2:  657 (80%) Hispanic, 74 (9%) African American, 90 (11%) White

Other relevant demographics:

Anthropometrics:  Both groups were comparable in maternal age, gestational age at entry into the program, and factors for the index of past pregnancy.

Location:  Group 1 - Bronx, New York,  Group 2 - San Antonio, Texas

Summary of Results:



Group 1 (Bronx)

Mean  + SE 

 Group 2 (San Antonio)

Mean + SE

Statistical Significance of Group Difference

Gestational age at testing start (wk)

29 + 6

 29   + 6


Weeks on reflectance meter

 10   + 1.3

 11   + 1.0


Total number of readings

 254  + 10

 261   + 8


Number of readings per week  30   + 2.0 29   + 1.2 NS
Readings >  mean, 120 mg/dL 27   + 1.5 26  + 0.8 NS
No attendance at diabetic clinic 0.6  + 0.1 0.6  + 0.2 NS

 NS = non-signficant

Other Findings


Author Conclusion:
Patient knowledge of the existance of a microchip in the reflectance meter dramatically improved patient performance and compliance. Patient performance reached only 70%. Social and ethnic diversity and geographic location did not affect patient performance regarding self-monitoring of blood glucose.
Funding Source:
University/Hospital: University of Texas Health Science Center at San Antonio, Incarnate word College, Albert Einstein College of Medicine/Montefiore Medical Center
Reviewer Comments:

Study was not blinded but high numbers and important findings. No stratification between pregestational versus gestational diabetics.  Inclusion/exclusion criteria not well defined.  Groups not similarly sized or similar in ethnicity.

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? No
  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? No
  2.2. Were criteria applied equally to all study groups? Yes
  2.3. Were health, demographics, and other characteristics of subjects described? No
  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) No
  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%.) N/A
  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? 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? ???
  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? No
  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? No
  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? No
  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