DF: Diabetes (2008)


Hanai H, Ikuma M, Sato Y, et al. Long-term effects of water-soluble corn bran hemicellulose on glucose tolerance in obese and non-obese patients: Improved insulin sensitivity and glucose metabolism in obese subjects. Biosci Biotechnol Biochem. 1997; 61: 1,358-1,361.

PubMed ID: 9301120
Study Design:
Non-randomized crossover trial
C - Click here for explanation of classification scheme.
Quality Rating:
Neutral NEUTRAL: See Quality Criteria Checklist below.
Research Purpose:

To examine the effect of soluble corn bran hemicellulose (CBH, 10g per day) on glucose control and serum insulin in three groups: Patients with impaired glucose tolerance (IGT) with or without obesity and with healthy non-obese controls.

Inclusion Criteria:
  • Impaired glucose tolerance
  • BMI higher than 26.4 for obese patients
  • Not undergoing medical treatment
  • Irregular exercise.
Exclusion Criteria:

None mentioned.

Description of Study Protocol:


Not described.


Recruited subjects that were informed of the details of the aims, contents and methods of the study and consented to participate of their own free will. None were undergoing medical treatment, all worked full-time and none exercised regularly.

All subjects participated for one year. For the first six months of the study, subjects ingested five grams of corn bran hemicellulose (CBH) twice a day with meals. No CBH was consumed for the last six months of the study. Data collected included anthropometric measurements (height and weight), 75-g oral glucose tolerance test and serum glucose levels, insulin response, HbA and GTT at zero, three, six and 12 months.  

Nutrient intake was recorded on case cards immediately after each meal for three days before entry into the study and after three months of CBH supplementation. The NUT version 3.0 program (Human Science Laboratory) was utilized to calculate energy, protein, fat, carbohydrate and dietary fiber. 


Five grams CBH, twice a day with meals for the first six months of the study.

Statistical Analysis 

  • Mean±SE
  • Freidman's two-way ANOVA
  • Paired T-test
  • Significance, P≤0.05.
Data Collection Summary:

Timing of Measurements

Data collected upon entry and at three, six and 12 months into the study:

  • 75g OGTT
  • Glucose
  • Insulin
  • HgbA1C.

Dependent Variables

  • Glucose
  • Insulin
  • HgbA1C.

 Independent Variables

CBH supplementation.

Control Variables

  • Weight
  • Presence of IGT.
Description of Actual Data Sample:

Initial N

38 (20 males, 18 females)

  • Obese IGT: 20 (10 males, 10 females)
  • Non-obese IGT: Eight (four males, four females)
  • Non-obese healthy volunteers: 10 (six males, four females).

Attrition (Final N)

Not described.


Range: 35 to 68 years

  • Obese IGT: 54.3±4.3
  • Non-obese IGT: 57.5±8.1
  • Non-obese healthy volunteers: 48.7±5.9.


Not descibed

Other Relevant Demographics

Not described.


 Body weight:

  • Obese IGT: 67.8±3.4
  • Non-obese IGT: 56.1±5.3
  • Non-obese healthy volunteers: 58.1±4.6.


Hamamatsu School of Medicine, Homamatsu, Japan.

Summary of Results:

Glucose Response

  • After six months on the usual diet supplemented with CBH (P<0.01), glucose intolerance in both the obese and non-obese impaired glucose tolerance subjects improved (P<0.05)
  • After six months on the usual diet supplemented with CBH (P<0.01), no differences were found in glucose response curves in the non-obese control subjects without impaired glucose tolerance  
  • Six months after discontinuing the CBH supplements, improvement in glucose tolerance was lost.


  • After six months on the usual diet supplemented with CBH (P< 0.01), HbA in the obese subjects decreased (P<0.05)
  • No changes were found in the non-obese and control subjects
  • Six months after discontinuing the CBH, HbA in obese subjects did not differ from that at entry into the study.

Serum Insulin

  • After six months of usual diet supplemented with CBH (P<0.01), serum insulin levels in seven of 20 obese subjects were decreased (P<0.05) 
  • Although not significant, fasting levels of serum insulin decreased by CBH supplementation in non-obese and control groups.
Author Conclusion:
  • The improved glucose tolerance test result was associated with improved insulin release and perhaps with peripheral insulin sensitivity
  • These findings suggest that corn bran hemicellulose (CBH) at a low dose might contribute to glucose control and would play a useful role in treating Type II diabetes patients.
Funding Source:
University/Hospital: Hamamatsu Unversity
Reviewer Comments:
  • Small sample size
  • Limited description of methods
  • Poorly designed study, as only eight subjects in the non-obese group compared to 20 subjects in the obese impaired glucose tolerance group.
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? ???
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? Yes
  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) N/A
  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")? No
4. Was method of handling withdrawals described? No
  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%.) No
  4.3. Were all enrolled subjects/patients (in the original sample) accounted for? ???
  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? Yes
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? Yes
  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? 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? Yes
  7.6. Were other factors accounted for (measured) that could affect outcomes? Yes
  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)? Yes
  8.5. Were adequate adjustments made for effects of confounding factors that might have affected the outcomes (e.g., multivariate analyses)? 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
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