EAL

Glycemic Index (2016)

Citation:

Afaghi A, Ghanei L, Ziaee A. Effect of low glycemic load diet with and without wheat bran on glucose control in gestational diabetes mellitus: A randomized trial. Indian J Endocr Metab. 2013; 17: 689-692.

PubMed ID: 23961487

Study Design:

Randomized Controlled Trial

Class:

A - Click here for explanation of classification scheme.

Quality Rating:

NEUTRAL: See Quality Criteria Checklist below.

Research Purpose:

To examine the effects of a low glycemic load diet that includes and does not include fiber on the frequency of requiring insulin in women with Gestational Diabetes Mellitus (GDM).

Inclusion Criteria:

Pregnant women
Impaired fasting glucose (IFG; FBS over 92) or impaired glucose tolerance (IGT; FBS less than 92; IGT one-hour, over 180mg per dL; two-hour, over 153mg per dL).

Exclusion Criteria:

None specifically stated.

Description of Study Protocol:

Recruitment: GDM patients that were referred to endocrine clinic in Iran
Design: Randomized trial. Patients that were IFG or IGT were randomly allocated to receive a low glycemic index (LGI), low glycemic load (LGL) diet with or without fiber.
Blinding used: None reported.

Intervention

Subjects were instructed to follow the LGI-LGL diets
Food lists were provided
Food items in the LGI-LGL diet had a glycemic index (GI) of no more than 20 and each main meal had an overall daily glycemic load (GL) of 67 to 72
All subjects followed the LGI-LGL diet for two weeks and caloric intake was recommended based on body weight
The Fiber Group included 15g wheat fiber in each main meal (three per day)
After two weeks, the women who achieved blood glucose control continued their diet; those who did not started on insulin therapy.

Statistical Analysis

Descriptive statistics reported as mean ±SD and frequency distribution
Independent T-tests and chi-square tests were used to compare within- and between-group differences in blood glucose concentrations.

Data Collection Summary:

Timing of Measurements
FBG and tw-hour post-prandial plasma blood glucose taken before intervention and after two weeks.

Dependent Variables

FBG
BG two-hours post-prandial.

Independent Variables

LGI-LGL diet with fiber (stated 15g wheat bran, three times daily).

Control Variables
None.

Description of Actual Data Sample:

Initial N

18 subjects in LGI-LGL Without Fiber Group
18 subjects in LGI-LGL With Fiber Group.

Attrition (Final N)

13 subjects final in LGI-LGL Without Fiber Group; 28% attrition
18 subjects in LGI-LGL With Fiber Group; 0% attrition.

Age

20 to 40 years
No mean provided
No differences between groups reported.

Ethnicity
Not specified.

Other Relevant Demographics

Gestation age, 24 to 28 weeks. No mean reported.
Differences between groups not reported.

Anthropometrics
BMI: 18.5 to 29 overall. Differences in groups not reported.

Location
Iran (assumed).

Summary of Results:

Key Findings

Variables	GI-GL With Fiber Group N=18	GI-GL Without Fiber Group N=13	Significance
FBS Before Intervention	100.4±16.3	108.0±20.3	P=0.2
FBS After Intervention	86.3±11.3	96.6±20.7	P=0.1
Pre-Post Differences Within Groups	P<0.001	P=0.01
BS 2-Hour Post-Prandial	115.1±18.1	136.9±18.7	P = 0.003

Reduction of fasting BS was 14% in the With Fiber Group and 12% in the Without Fiber Group
Reduction of two-hour post-prandial BS was 29.6% in the With Fiber Group and 21.3% in the Without Fiber Group
11 subjects (61.1%) in the With Fiber Group and three (23.1%) in the Without Fiber Group achieved blood glucose control (P=0.04)
Seven (38.9%) in the With Fiber Group and 10 (76.9%) in the Without Fiber Group required insulin
Subjects in the With Fiber Group were 5.2 more likely to achieve blood glucose control (P=0.04).

Author Conclusion:

The low glycemic index diet containing extra added fiber for women with GDM is appropriate, safe and well tolerated
A low glycemic load diet with fiber significantly reduces the need for the use of insulin.

Funding Source:

University/Hospital:

Qazvin Metabolic Diseases Research Center, Qazvin Univ of Med Sciences

Reviewer Comments:

Eligibility criteria not specified
Method of randomization not clearly outlined
Not clear as to how the diet was provided; threat to external validity
Between-group differences not reported for demographic variables or potential confouncers such as exercise, adherence to diet, BMI.

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?	???
	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?	???
3.	Were study groups comparable?		Yes
	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?	???
	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?	No
	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?		No
	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.)	No
	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?		No
	6.1.	In RCT or other intervention trial, were protocols described for all regimens studied?	No
	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?	No
	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?	???
	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?		No
	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?	???
	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)?	No
	8.5.	Were adequate adjustments made for effects of confounding factors that might have affected the outcomes (e.g., multivariate analyses)?	No
	8.6.	Was clinical significance as well as statistical significance reported?	No
	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?		No
	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