DF: Diabetes (2008)
Jenkins DJ, Goff DV, Leeds AR, Alberti KG, Wolever TM, Gassull MA, Hockaday TD. Unabsorbable carbohydrates and diabetes: Decreased post-prandial hyperglycaemia. Lancet. 1976 Jul 24; 2 (7978): 172-174. PMID: 73796.
PubMed ID: 73796
To examine the effects of fiber, in the form of guar powder and pectin, on blood glucose concentrations in individuals with diabetes.
- Non-insulin-dependent diabetic
- Insulin-dependent diabetic.
Not described.
- Recruitment: Not described
- Design: Randomized crossover study of 11 diabetic patients to test meal (breakfast) with or without fiber-supplemented bread (16g guar gum, 10g pectin). A one- to two-week washout period occurred between meals.
- Blinding used: N/A.
Intervention
- Subjects were randomly assigned to consume a test breakfast either with or without fiber supplementation
- The intervention meal included fiber-supplemented bread (16g guar gum, 10g pectin) and the control meal did not
- Individuals on oral hypoglycemic agents did not take their medication on test days
- Insulin-requiring individuals did take their insulin
- Following a 14-hour fast, subjects consumed the assigned breakfast in 15 to 20 minutes
- Serum glucose and insulin levels were collected at zero, 15, 30, 45, 60, 90, 120, 150 and 180 minutes post-prandial
- Subjects underwent a one- to two-week washout period prior to crossing-over to the other test group.
Statistical Analysis
- Means with standard error
- Student’s T-test (paired data).
Timing of Measurements
The following data was collected at 0, 15, 30, 45, 60, 90, 120, 150, 180 minutes post-prandial of the two test meals:
- Serum glucose
- Serum insulin.
Dependent Variables
- Serum glucose
- Serum insulin.
Independent Variables
Fiber intake.
- Initial N: 11 (six males, five females); eight insulin independent (four male, four female); three insulin-requiring (two males, one female)
- Attrition: Not described.
Age
- Insulin independent: 58±5 years
- Insulin-requiring: 21 years.
Ethnicity
Not described.
Anthropometrics
- Insulin independent: 120%±11% DBW
- Insulin-requiring: 105%±3% DBW.
Location
General Hospital, Southampton and Radcliffe Infirmary; Oxford, England.
Serum Glucose; Insulin Independent Diabetes (N=8)
- Significantly lower following fiber-containing meal at:
- 30 minutes (2.61±0.61mmol per L, P<0.01)
- 45 minutes (3.45±0.95mmol per L, P<0.01)
- 60 minutes (3.56±0.95mmol per L, P<0.01)
- 90 minutes (3.06±0.95mmol per L, P<0.02).
Serum Glucose; Insulin-Requiring Diabetes (N=3)
Significantly lower following fiber-containing meal (data not reported).
Serum Insulin; Insulin Independent Diabetes (N=8)
- Significantly lower following fiber-containing meal at:
- 30 minutes (11±4 milliunits per L, P<0.05)
- 45 minutes (19±6 milliunits per L, P<0.02)
- 60 minutes (22±5 milliunits per L, P<0.01)
- 90 minutes (24±5 milliunits per L, P<0.002)
- 120 minutes (19±4 milliunits per L, P<0.01).
Fiber-enriched diets, including guar gum and pectin, significantly decrease blood glucose concentrations and serum-insulin in individuals with type 1 and type 2 diabetes.
Government: | US Public Health Service, Swiss National Research Foundation | ||
Not-for-profit |
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- Small sample size, which is even smaller when broken down by type of DM
- No description of inclusion or exclusion criteria
- Limited presentation of demographic data
- Large difference in age between insulin and non-insulin-requiring groups
- No power calculation presented
- No description of diet composition
- No data collected or presented on baseline (pre-meal) serum glucose or insulin levels
- No description of randomization scheme
- No description of diet tolerance.
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? | Yes | |
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? | No | |
3.1. | Was the method of assigning subjects/patients to groups described and unbiased? (Method of randomization identified if RCT) | No | |
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.) | 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? | No | |
4.1. | Were follow-up methods described and the same for all groups? | No | |
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%.) | No | |
4.3. | Were all enrolled subjects/patients (in the original sample) accounted for? | No | |
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.) | 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? | 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? | Yes | |
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? | 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? | No | |
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? | No | |
8.2. | Were correct statistical tests used and assumptions of test not violated? | No | |
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? | 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 | |