DF: Diabetes (2008)
- type 2 diabetes
Recruitment: subjects drawn from patient pool at diabetes clinic and from respondents to public advertisements; subjects received a financial award for their participation
Design open-label, randomized crossover design with six treatment segments
Blinding used (if applicable): none
Intervention (if applicable): subjects were given, in random order, test meals with 50 g of available carbohydrate in the form of
- white bread (3 trials)
- commercial oat bran breakfast cereal
- prototype beta-glucan-enriched (6.5%) breakfast bar
- prototype beta-glucan-enriched (8.1%) breakfast cereal
Statistical Analysis
- the significance of differences between mean glycemic response areas among the four test meals was assessed using a two-way ANOVA and after establishment of a significant F-value, by the Student-Neuman-Keuls procedure.
- the incremental areas under the blood glucose-response curve, ignoring the area below the fasting level, were calculated geometrically.
- the area under the curve for each food was expressed as a percentage of the mean area for the three white bread tests and the resulting mean values for all subjects represented the GI of the food.
- four volunteers were asked to repeat test sessions and means of all the tests for the food were used to calculate the GI.
Timing of Measurements
- capillary blood samples taken fasting and then 30, 60, 90,120, 150, and 180 minutes after the start of the meal
Dependent Variables
- palatablility using a bipolar scale ranging from -3 (dislike extremely) to +3 (like extremely)
- blood glucose response, using finger prick blood samples and analyzed using glucose oxidase method
- total cholesterol, tryglycerides, and HDL using desktop Cholestech LDX analyzer
Independent Variables
- test meals with 50 g of available carbohydrate in the form of
- white bread (3 trials)
- commercial oat bran breakfast cereal
- prototype beta-glucan-enriched (6.5%) breakfast bar
- prototype beta-glucan-enriched (8.1%) breakfast cereal
Control Variables
Initial N: 16; 10 men, 6 women
Attrition (final N): 16
Age: 61±1.8 y, range 46-70
Ethnicity: not specified
Other relevant demographics:
- HbA1c 7.4±0.4%, range 5.5±11.4%
Anthropometrics
- BMI 29±1.6, range 19.4-43.0
Location: Canada
All meals were highly acceptable to volunteers.
The blood glucose levels for both the prototype beta-glucan bar and beta-glucan cereal were significantly lower at 60, 90, and 120 minutes than white bread (P<0.05).
Variables |
Incremental area under the blood glucose curve |
Predicted GI |
Observed GI |
GI reduction of beta-glucan |
Palatability Score |
Oat Bran breakfast cereal |
593±80 |
99 |
86±6 ** |
3.2±1.7
|
1.5±0.2 |
beta-glucan cereal |
295±41* |
79 |
52±5** |
3.7±0.7 |
2±0.2 |
beta-glucan bar |
355±49* |
74 |
43±4** |
5.0±0.7 |
1.5±0.2*** |
*significantly lower than for white bread
**significantly lower than for white bread
***significantly greater than the value for white bread (P<0.05)
Other Findings
Quality Criteria Checklist: Primary Research
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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? | 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.) | 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? | 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.) | 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? | 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? | 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? | N/A | |
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)? | 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? | 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? | No | |
10.2. | Was the study free from apparent conflict of interest? | Yes | |