EAL

DM: Carbohydrates (2007)

Citation:

Study Design:

Class:

- Click here for explanation of classification scheme.

Quality Rating:

Research Purpose:

To evaluate the incorporation of low-GI carbohydrates into daily menu planning as an effective behavioral lifestyle change to improve glycemic control and weight management in patients with type 1 and 2 diabetes.

Inclusion Criteria:

type 1 or type 2 diabetes
stable or improved current HbA1c and BMI values after initiation of low-GI MNT with no increase in number and/or dosages of oral antidiabetic drugs and/or insulin
A minimum of 2 hours of LGI-MNT counseling from the investigator within the time frame of September 1, 2001 through May 1, 2004

Exclusion Criteria:

did not complete required 2 hours of medical nutrition therapy (MNT)
weight gain after receiving MNT
no improvement in HbA1c levels after MNT
required increased medication after MNT

Description of Study Protocol:

Recruitment : referred to primary investigator by physicians for MNT

Design:

A one-on-one structured interview, consisting of the GIFQ and the IQ was conducted by the primary investigator
interview time varied from 45 to 60 minutes
no subject received any review of GI information prior to the interview
responses were based solely on memory of LGI-MNT counseling sessions, 62% of which had occured more than one year earlier.
all responses and comments were audiotaped and transcribed verbatim and coded for accurate data collection
6 randomly-selected subjects retook the GIFQ after 6-8 months had lapsed from their original interview date to ensure the reproducibility of the GIFQ results
all interview texts and test answers were independently reviewed by two Registered Dietitians not associated with the study.

Blinding used (if applicable): none, but investigator was not present when participants were recording their answers, except in 3 cases where the subjects needed assistance.

Intervention (if applicable): not applicable

Statistical Analysis

Pre- and post-counseling HbA1c, BMI, and GI values of meals were analyzed by paired -sample t tests
an inter-item correlation was used to determine the reliability of the GIFQ. A t test was used to compare the test-retest results for the GIFQ for the 6 recalled subjects
descriptive statistics used to explain the qualitative findings of the IQ responses

Data Collection Summary:

Timing of Measurements: the interviews were conducted between 3 and 36 months after the initial LGI-MNT counseling

Dependent Variables

HbA1c; values retrieved from medical charts
BMI; from medical charts
GI values of meals; from 1-day food diaries collected on interview day
response to Glycemic Index Foods Quiz (GIFQ), 10-item measure constructed by primary investigator to measure conceptual and practical knowledge
responses to Interview Questionnaire (IQ); a qualitative tool designed to elicit each participant's appraisal of his or her use of low-GI carbohydrate choices as an effective self-management strategy

Independent Variables

average number of office visits for MNT counseling was 5
average counseling time was 3.6 hours

Control Variables

Description of Actual Data Sample:

Initial N: 21; 12 women, 9 men

Attrition (final N): 21.

Age: 21-89

Ethnicity: not specified

Other relevant demographics:

3 subjects with type 1 diabetes, one with new onset
18 subjects with type 2 diabetes, duration of disease ranging from less than 1 year (38%) to 45 years

Anthropometrics :stable weight prior to interview

Location: United States

Summary of Results:

Variables	Pre-LGI-MNT	Post-LGI-MNT	Mean Decrease, %
HbA1c, %	7.5±1.3	6.0±0.7	19.4*
BMI	35.1±11.4	32.3±9.1	8.0**
Glycemic Index Value of Meals	59±7.7	44±0.2	25.2*

*P<.0005

**P=.002

Other Findings

all 3 type 1 subjects reduced their daily insulin dosages postcounseling between 33 and 58%
of type 2 subjects, 2 subjects who were taking oral anitdiabetic agents were able to discontinue them; the only subject taking insulin was able to decrease the dose by 20%
the average GIFQ score was 86.2%; conceptual understanding of the relationship between carbohydrates and diabetes was assessed at 96%; practical knowledge of low-/high-GI carbohydrates was assessed at 76%
findings from the Interview Questionnaire:
- 90% lacked understaning of GI before MNT counseling
- subjects had a 100% belief that low-GI carbohydrates are helpful
- unanimous agreement that behavioral change is a more effective approach to glycemic and weight control than "dieting"
- 100% believed that they would continue to use the GI concept as a permanent lifestyle change

Author Conclusion:

The findings clarify the benefit of incorporating low-GI carbohydrates into the daily food choices of free-living diabetes patients.

Funding Source:

Reviewer Comments:

Small sample with very broad demographics.

Only successful patients were included in the study (stable or improved BMI and HbA1c). Of 199 total patients seen, only 21 showed enough evidence of success to be included in this study.

A one-day food diary can be used to assess the intake of a population, but this population of 21 is rather small for this use.

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?	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?	No
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)	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?	Yes
	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?	Yes
	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?	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?	Yes
	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?	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?		No
	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?	No
	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?	No
	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?	No
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)?	No
	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