EAL

DF: Diabetes (2008)

Citation:

Study Design:

Class:

- Click here for explanation of classification scheme.

Quality Rating:

Research Purpose:

To evaluate the effects of a diet rich in natural (NF) or extractive fibers (guar gum) on serum levels of pyruvate, lactate, 3fiHO-butyrate and amino acids, among men with insulin-dependent diabetes.

Inclusion Criteria:

Male
Type 1 diabetics
Stable body weight during the two months preceding the study
Within 15% of their ideal body weight, according to Lawrence (ideal body weight; mean plus SE=111±2.3)
On conventional insulin therapy: Regular insulin (Actrapid Novo) at each meal and lente insulin (Lente-Novo) in the morning, in the evening or both.

Exclusion Criteria:

No signs of heart, liver or pancreatic disease or microangiopathy.

Description of Study Protocol:

Recruitment

Not described.

Design

All subjects consumed a standard isocaloric diet (40% carbohydrate, 40% lipid, 20% protein and 30g of natural fiber) for four weeks. Subjects were then randomly assigned to isocaloric high-fiber diets, enriched with either natural or extracted fibers.
Assignment was not described
Compliance to diet was assessed weekly by a dietitian
The patients maintained their normal activity during the study.

Composition of Isocaloric Meals

	Standard	High Natural Fiber	Added Guar Gum
Carbohydrate (%)	40%	58%	50%
Lipids (%)	40%	30%	30%
Protein (%)	20%	12%	20%
Fiber (g/d)	30g	70g	30g
Guar Gum (g/d)	0g	0g	9g

Subjects returned to the clinic every two weeks and the following data was collected:

Survey on GI tolerance
Laboratories (after a midnight fast)
- Serum glucose
- Lactate
- Pyruvate
- Three-beta-hydroxybutyrate
- Glucagon
- Growth hormone
- C-peptide
- HgbA1C
- Amino acid levels
- Lipids
  - Total cholesterol
  - Triglycerides
  - HDL.

Blinding Used

Not specified.

Intervention

Regimen A: Enriched with foods of high fiber content (peas, beans, spinach, cauliflowers, artichokes, string beans, fennel). The fibre content was determined on the basis of the Italian bromatological table of 'Ministero dell’Agricoltura e delle Foreste e lstituto Nazionale della Nutrizione.'
Regimen B: Supplemented with fibres extracted from guar gum, granulated and given to the patients three times a day in water before meals.

Statistical Analysis

Paired and unpaired student’s T-tests
Chi-square test.

Data Collection Summary:

Timing of Measurements

Subjects returned to the clinic every two weeks and the following data was collected:

Survey on GI tolerance
Laboratories (after a midnight fast)
- Serum glucose
- Lactate
- Pyruvate
- 3-ß-Hydroxybutyrate
- Glucagon
- Growth Hormone
- C-Peptide
- HgbA1C
- Amino Acid levels
- Lipids
  - Total Cholesterol
  - Triglycerides
  - HDL.

Dependent Variables

Serum glucose
Lactate
Pyruvate
3-beta-hydroxybutyrate
Glucagon
Growth hormone
C-peptide
HgbA1C
Amino acid levels
- Lipids
- Total cholesterol
- Triglycerides
- HDL.

Independent Variables

Intake of high natural fiber (Regimen A)
Intake of guar gum fiber (Regimen B).

Control Variables

None specified.

Description of Actual Data Sample:

Initial N: 12 diabetic men; 10 controls
Attrition (final N): None mentioned (12)
Age: 44±2 years
Ethnicity: Not reported.

Other Relevant Demographics

Duration of diabetes: 16± two years
Insulin requirement: 47± three units per day
Fasting glucose: 201±19 mg per dL
HgbA1c: 8.1±0.4%
Fasting C-peptide: 0.61±0.12ng per ml.

Anthropometrics

Body weight stable during the two months preceding the study
Body weight within 15% of their ideal body weight, according to Lawrence (ideal body weight, mean±SE=111±2.3).

Location

Malattie del Ricambio, Istituto di Medicina Ciinica; Universitad di Padova; Padova, Italy.

Summary of Results:

Variables

High Natural Fiber (Before)

Measures and Confidence Intervals

High Natural Fiber (After)

Guar gum
(Before)

Measures and Confidence Intervals

Guar Gum (After)

Statistical Significance of Group Difference

HbA1c (%)

8.1±0.3

7.1±0.4*

8.1±0.5

7.7±0.3

*P<0.0005

Plasma C-peptide (ng/ml)

0.78±0.18

0.57±0.13*

0.8±0.1

0.63±0.1**

*P<0.025
**P<0.02

Other Findings

No significant differences in the following, based on diet regimen:
- Blood glucose
- Lactate
- Pyruvate
- Three-beta-hydroxybutyrate
- Plasma glucagon
- Plasma growth hormone
- Serum lipids (cholesterol, serum triglycerides, HDL-cholesterol)
- Glycosuria.
Insulin requirement: Both diet interventions prodicted a non-significant reduction in insulin requirement (from 47±3U per day to 41±2U per day)
Amino acids
- Following one month of standard (non-intervention) diet, diabetics had higher serum levels of branched-chain amino acids (leucine, isoleucine, valine) than controls and these values returned to normal under both dietary regimens
- Plasma levels of phenylalanine and lysine did not change significantly under either dietary regimen
- Both groups showed a significant decrease in plasma levels of tryptophan (P<0.02)
- Serine significantly decreased (P<0.005) with natural fibers.
Side effects
- Similar side effect between groups
- More satiety in guar gum group (P<0.01).

Author Conclusion:

These data suggest that fibres, natural or extractive when present in the diet in adequate amounts, improve both metabolic control and protein metabolism in diabetic patients.

Funding Source:

Government:

CNR

Reviewer Comments:

Less than 20 subjects per group
Poor description of study population
Many outcomes measured, unclear what was primary vs. secondary
No "Ns" in any of the tables, so there is uncertainty whether all participants are accounted for
No discussion of blinding
No description of intervention length
Did not report between-group comparisons (unpaired T-tests)
No power calculations
No information on the control group, other than one line in the text and information in the results tables
Multiple tests without adjustment for comparisons.

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
	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
	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
	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
	4.	Is the intervention or procedure feasible? (NA for some epidemiological studies)	Yes

Validity Questions
	1.	Was the research question clearly stated?	No
1.	Was the research question clearly stated?		No
	1.1.	Was (were) the specific intervention(s) or procedure(s) [independent variable(s)] identified?	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
	1.2.	Was (were) the outcome(s) [dependent variable(s)] clearly indicated?	Yes
	1.3.	Were the target population and setting specified?	No
	1.3.	Were the target population and setting specified?	No
	2.	Was the selection of study subjects/patients free from bias?	???
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?	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?	???
	2.2.	Were criteria applied equally to all study groups?	???
	2.3.	Were health, demographics, and other characteristics of subjects described?	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?	???
	2.4.	Were the subjects/patients a representative sample of the relevant population?	???
	3.	Were study groups comparable?	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
	3.1.	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?	???
	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.)	???
	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
	3.4.	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
	3.5.	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
	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.	Was method of handling withdrawals described?		No
	4.1.	Were follow-up methods described and the same for all groups?	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
	4.2.	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
	4.3.	Were all enrolled subjects/patients (in the original sample) accounted for?	No
	4.4.	Were reasons for withdrawals similar across groups?	???
	4.4.	Were reasons for withdrawals similar across groups?	???
	4.5.	If diagnostic test, was decision to perform reference test not dependent on results of test under study?	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.	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
	5.1.	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
	5.2.	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
	5.3.	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
	5.4.	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
	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.	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?	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?	N/A
	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?	???
	6.3.	Was the intensity and duration of the intervention or exposure factor sufficient to produce a meaningful effect?	???
	6.4.	Was the amount of exposure and, if relevant, subject/patient compliance measured?	No
	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
	6.5.	Were co-interventions (e.g., ancillary treatments, other therapies) described?	No
	6.6.	Were extra or unplanned treatments 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
	6.7.	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
	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.	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
	7.1.	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
	7.2.	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?	???
	7.3.	Was the period of follow-up long enough for important outcome(s) to occur?	???
	7.4.	Were the observations and measurements based on standard, valid, and reliable data collection instruments/tests/procedures?	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
	7.5.	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
	7.6.	Were other factors accounted for (measured) that could affect outcomes?	No
	7.7.	Were the measurements conducted consistently across groups?	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?	No
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
	8.1.	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
	8.2.	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
	8.3.	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)?	???
	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)?	???
	8.5.	Were adequate adjustments made for effects of confounding factors that might have affected the outcomes (e.g., multivariate analyses)?	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?	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?	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.	Are conclusions supported by results with biases and limitations taken into consideration?		Yes
	9.1.	Is there a discussion of findings?	Yes
	9.1.	Is there a discussion of findings?	Yes
	9.2.	Are biases and study limitations identified and discussed?	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.	Is bias due to study's funding or sponsorship unlikely?		Yes
	10.1.	Were sources of funding and investigators' affiliations described?	Yes
	10.1.	Were sources of funding and investigators' affiliations described?	Yes
	10.2.	Was the study free from apparent conflict of interest?	Yes
	10.2.	Was the study free from apparent conflict of interest?	Yes