EAL

GDM: Monitoring (2008)

Citation:

Study Design:

Class:

- Click here for explanation of classification scheme.

Quality Rating:

Research Purpose:

To compare the daily glycemic profile reflected by continuous versus self-monitoring of blood glucose in women with GDM and to evaluate possible differences in treatment strategy based on the 2 monitoring methods.

Inclusion Criteria:

All women had GDM according to criteria of Fourth International Workshop - Conference on Gestational Diabetes Mellitus using a 100 g load for the OGTT

Exclusion Criteria:

None specifically mentioned.

Description of Study Protocol:

Recruitment

Consecutive patients with GDM were recruited during a routine clinical visit to the Diabetes in Pregnancy Center of the Perinatal Division, Rabin Medical Center in Israel. Additional pregnant women with GDM were studied in Santa Barbara, California; recruitment methods not described.

Design: Time Series Study

Blinding used (if applicable): not applicable. Data collected from self-monitoring and CGM for each patient were evaluated separately by single experienced physician in each institution.

Intervention (if applicable)

Data derived from Continuous Glucose Monitoring System (MiniMed) for 72 hours were compared to fingerstick glucose measurements (6-8 times a day).
Israeli women were instructed to measure both 1 hour and 2 hour postprandial glucose levels during 1 week of strict diet prior to insulin treatment
Insulin treatment instituted if fasting glucose levels exceeded 90 mg/dl and/or 1 hour postprandial glucose concentrations exceeded 140 mg/dl

Statistical Analysis

Pearson correlation coefficients and their significance were calculated between the variables. The chi-square test was used to compare categorical variables, and the Student's t test to determine the statistical significance of differences in mean continuous parameters.

Data Collection Summary:

Timing of Measurements

Prior to sensor placement, hbA1c, fructosamine and plasma glucose were measured. Data derived from Continuous Glucose Monitoring System (MiniMed) for 72 hours were compared to fingerstick glucose measurements (6-8 times a day). During continuous monitoring, patients documented the timing of food intake, insulin injections and hypoglycemic events.

Dependent Variables

Levels of hemoglobin A1c, fructosamine and plasma glucose measured
Timing of food intake
Insulin injections
Hypoglycemic events

Independent Variables

Data derived from Continuous Glucose Monitoring System (MiniMed) for 72 hours were compared to fingerstick glucose measurements with glucometer (6-8 times a day).

Control Variables

Demographic data from patient charts: gravidity, parity and BMI

Description of Actual Data Sample:

Initial N: 57 women with GDM, 47 in Israel and 10 in California

Attrition (final N): 57 women. In Israeli group, 23 women were treated by diet alone, 24 by diet and insulin. All 10 American women were treated with insulin.

Age: see Results

Ethnicity: not mentioned

Other relevant demographics: see Results

Anthropometrics: Gestational age ranged from 24 - 32 weeks in Israeli women, 32 - 36 weeks in American women

Location: Israel and California

Summary of Results:

	Israeli Group (diet treated)	Israeli Group (diet plus insulin)	American Group (diet plus insulin)
Number of patients	23	24	10
Age (years)	29 ± 5.1	31.2 ± 4.7	29 ± 2.7
Gestational age (weeks)	28 ± 3.3	27.8 ± 3.6	34 ± 1.5
Gravidity	2.1 ± 0.8	2.4 ± 0.9	3 ± 1.5
Parity	1.8 ± 0.4	1.8 ± 0.3	2.5 ± 1.0
BMI	28.1 ± 4.3	29.3 ± 3.6	31 ± 3.2
Hemoglobin A1c (%)	5.1 ± 0.9	5.6 ± 0.7	5.2 ± 0.7
Fructosamine (mg/dl)	253 ± 33	277 ± 41	Not applicable
CGM-mean glucose level (mg/dl)	98 ± 10.6	119 ± 13.6	103 ± 11.3
SM-mean glucose level (mg/dl)	87 ± 11.2	103 ± 7.2	92 ± 5.7

Other Findings

Israeli women:

An average of 763 ± 62 glucose measurements was recorded for each patient with continuous glucose monitoring.

The mean total time of hyperglycemia (glucose level > 140 mg/dl) undetected by the fingerstick method was 132 ± 31 minutes/day in the insulin-treated group and 94 ± 23 minutes/day in the diet-treated group.

Nocturnal hypoglycemic events (glucose levels < 50 mg/dl) were recorded in 14 patients, all insulin-treated.

On the basis of the additional information provided by continuous monitoring, the therapeutic regimen (insulin therapy, diet adjustment or both) was changed in 36 of 47 patients.

American women:

The mean time of undetected hyperglycemia for a total group monitoring time of 30 days was 78 ± 13 minutes/day.

8 women had nocturnal hypoglycemia on at least 1 of the 3 nights of monitoring for a total of 12 nights.

A change in insulin dosage was made in all women on the basis of the data provided by continuous glucose monitoring.

Author Conclusion:

Continuous glucose monitoring is helpful for monitoring women with GDM and for adjusting diabetes therapy. It can accurately detect high postprandial blood glucose levels and nocturnal hypoglycemic events that may go unrecognized by intermittent blood glucose monitoring. A large prospective study on maternal and neonatal outcome is needed to determine the clinical implications of this new monitoring technique.

Funding Source:

Reviewer Comments:

Recruitment methods of American women not described. Groups studied at different gestational ages. Authors note short study time period.

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?		???
	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?	???
	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?		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?	???
	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?	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?	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?	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)?	N/A
	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