EAL

GDM: Monitoring (2008)

Citation:

Study Design:

Class:

- Click here for explanation of classification scheme.

Quality Rating:

Research Purpose:

To determine the postprandial glucose profile in the diabetic pregnancy.

Inclusion Criteria:

Gravid women with type 1 diabetes mellitus and GDM
Type 1 diabetes diagnosed before pregnancy
GDM diagnosed according to criteria of Carpenter and Coustan

Exclusion Criteria:

None specifically mentioned.

Description of Study Protocol:

Recruitment

Subjects recruited from the diabetic populations of the Rabin Medical Center and St. Luke's-Roosevelt Hospital Center.

Design: Time Series Study

Blinding used (if applicable): Patients were unaware of the results of the sensor measurements during the monitoring period and did not use the fingerstick capillary glucose measurements during the study.

Intervention (if applicable)

Subjects treated by diet and insulin as indicated
Diet involved caloric restriction and subjects were counseled by a nutritionist about a diet regimen of 3 meals and 4 snacks daily
Insulin added after diet therapy alone failed to maintain the fasting plasma glucose > 105 mg/dl or 2 hours values > 120 mg/dl or both

Statistical Analysis

Student t test and univariate ANOVA tests were used for normally distributed continuous data
For abnormally distributed continuous variables, the Mann-Whitney, Kruskal-Wallis, or Friedman's nonparametric test was used
Chi-squared test used for categoric data
Coefficient of variation with Levene's test for equality of variances was calculated for postprandial blood glucose values for each group
For the main dependent variable, 22 meals for each group would result in 80% power to detect a difference of 30 minutes

Data Collection Summary:

Timing of Measurements

Subjects were connected to a continuous glucose monitoring system for 72 consecutive hours. Women were instructed to record the time of each meal during the study period. For each subjects, 3 meals were analyzed, and for each meal, the first 240 minutes were analyzed.

Dependent Variables

Blood glucose values measured using continuous glucose monitoring system (MiniMed)

Independent Variables

Type 1 diabetes or GDM
Time of food intake
Insulin injections
Exercise periods
Symptomatic hypoglycemic events

Control Variables

Description of Actual Data Sample:

Initial N: 65 women: 26 with GDM treated by diet alone, 19 with GDM receiving insulin therapy, and 20 had type 1 diabetes

Attrition (final N): as above

Age:

29.0 ± 4.1 years for subjects with type 1 diabetes
32.2 ± 5.0 years for subjects with diet-treated GDM
35.6 ± 4.8 years for subjects with insulin-treated GDM

Ethnicity: not mentioned

Other relevant demographics:

Anthropometrics: Insulin-treated patients with GDM had older maternal age, higher gravidity and parity, and higher BMI compared with subjects with type 1 diabetes mellitus or diet-treated GDM.

Location: Rabin Medical Center in Israel, St. Luke's-Roosevelt Hospital in New York

Summary of Results:

Postprandial Peak Times

	Breakfast	Lunch	Dinner	P value
Type 1 diabetes (n=20)	88.8 ± 42.5	103.3 ± 44.4	88.6 ± 33.1	0.88
Diet-treated GDM (n=26)	77.6 ± 31	87.8 ± 34	87.6 ± 28	0.10
Insulin-treated GDM (n=25)	75.6 ± 30.3	83.7 ± 41.4	102.8 ± 46.6	0.10

Postprandial Peak Values

	Breakfast	Lunch	Dinner	P value
Type 1 diabetes (n=20)	180.1 ± 68	196.2 ± 68	168.6 ± 55	0.48
Diet-treated GDM (n=26)	130.5 ± 22	127.4 ± 30	140.0 ± 33	0.30
Insulin-treated GDM (n=25)	133.7 ± 39.5	147.1 ± 48.4	159.2 ± 49.8	0.004

Other Findings

The time interval from meal to peak postprandial glucose levels was similar in all the evaluated types of diabetic pregnancies and in good and poor control insulin-treated patients with GDM (approximately 90 minutes).

Failure to return to preprandial glucose values within a 3-hour observation period was identified in approximately 50% of the patients.

A similar postprandial glucose peak time was obtained for breakfast, lunch and dinner in all study groups.

Postprandial hypoglycemia events were noted in approximately 10% of the meals and occurred about 160 minutes after mealtime.

Author Conclusion:

In conclusion, the continuous glucose monitoring system enabled us to characterize postprandial glucose profile in diabetic pregnancies. Our study determined that the mean time to peak postprandial glucose in 3 categories of women with diabetes mellitus is approximately 90 minutes. This information should be considered in the treatment of diabetes mellitus in pregnancy.

Funding Source:

Reviewer Comments:

Study completed in Israel and United States. Groups of subjects had statistically significant differences.

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?	???
	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?		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.)	???
	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?	N/A
	6.2.	In observational study, were interventions, study settings, and clinicians/provider described?	Yes
	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?	N/A
	6.6.	Were extra or unplanned treatments described?	N/A
	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?	Yes
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?	No
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