EAL

DM: Carbohydrates (2007)

Citation:

Study Design:

Class:

- Click here for explanation of classification scheme.

Quality Rating:

Research Purpose:

To investigate, in a 6-week home-based feeding study, the effect on blood glucose and the acceptability to families of substituting naturally available high-fiber whole foods for the traditional low-fiber foods in the diets of diabetic children.

Inclusion Criteria:

Children with diabetes willing to participate in the study

Exclusion Criteria:

None given

Description of Study Protocol:

Recruitment

Not provided

Design

Comparison of glycemic control in 10 children with type 1 diabetes during and at the end of 6 weeks of a controlled nutrient diet containing 1 g fiber/100 calories (refined diet) vs 6 weeks of the same type of diet but with 3 g fiber/100 calories (unrefined diet).

Blinding used (if applicable)

Intervention (if applicable)

Subjects were randomized (sequentially) to either a refined diet (1 g fiber/100 cal, or 20 g/d) or an unrefined diet (3 g fiber/100 cal, or 60 g/d) for six weeks, and then were crossed over to the other diet (no washout period described). The diets were identical except for the type and structure of the carbohydrate: 30% of energy as fat with a ratio of saturated to total mono- and polyunsaturated fats of 1:1; 15% protein with at least 40% of this animal protein; 55% as carbohydrate with a constant ratio of simple to complex sugars of 2:3; the refined diet carbohydrate was based on refined grains, processed fruits and vegetables, milk and yogurt; the unrefined diet carbohydrate was based on whole grains, fresh fruit and vegetables, and dried beans. Diets were calculated individually for each child, recipe books and individual meal plans were devised for each diet, and families were taught how to use them at home by a research dietitian. At the end of each six week period, control achieved was assessed under standard conditions at home during a 24-hr "profile" day. During each 6-week period, 24-hr diet histories were taken to assess degree of compliance; both the dietitian and physician phoned each family weekly; and every 2 weeks a physician did a home visit.

Statistical Analysis

Wilcoxon's rank sum test to compare differences between data pairs
Analysis of variance

Data Collection Summary:

Timing of Measurements

Baseline; 2 through 6 weeks (patient generated information); 6th week profile; 6 months after study (24-hr food recall only)

Dependent Variables

glycosylated hemoglobin small column ion exchange method)
blood glucose (hexokinase method)
c-peptide (charcoal separation radioimmunoassay after polyethylene glycol extraction)
Urine glucose (glucose oxidase method)

Independent Variables

dietary fiber (calculated from British food tables - McCance and Widdowson, 4th ed, 1978)

Control Variables

growth of the children (height, weight)

Description of Actual Data Sample:

Initial N: 10 children (4 girls, 6 boys)

Attrition (final N): none reported, 10

Age: mean age of 14.1 yrs (range 11.3-17.0 yrs)

Ethnicity: not reported

Other relevant demographics:

duration of diabetes: 4.7 yrs (range 9 mo to 14 yrs)
Insulin management: once-daily injection of Monotard and Actrapid (Novo)
average glycosylated hemoglobin: 11.4% (range 9.1-16.0)
C-peptide: 5 children were classiied as c-peptide producers

Anthropometrics ;

Height: 50th percentile (range 25-90)
Weight: 70th percentile (range 10-90)
Two children had not begun their growth spurt; 3 were approaching maximum height velocity, and 5 had passed peak height velocity.

Location: John Radcliffe Hospital Oxford, UK

Summary of Results:

Variables	Unrefined Diet, 6th wk profile day mean (SE)	Refined diet (control), 6th wk profile day mean (SE)	Statistical Significance of Group Difference at 6 wks
24-hr blood glucose (mmol/l)	6.9 (0.5)	9.0 (1.1)	p < 0.01
24-hr urine glucose (g/24 h)	9.3 (1.2)	38.0 (14.7)	p< 0.01
change in glycosylated hemoglobin (%)	-0.76 (0.35)	-0.18 (0.40)	NS
Preprandial blood glucose (mean of values before breakfast, midday, and the 1800-hr meals) (mmol/l)	5.5 (0.3)	8.4 (0.3)	p<0.01
Postprandial blood glucose (mean of values 2 hr after 3 main meals) (mmol/ll)	8.5 (0.3)	12.2 (0.3)	p<0.001

Other Findings

Author's hypothesis, that "the use of whole foods high in dietary fiber would retard carbohydrate absorption, and so match more closely the absorption of the injected insulin than could the traditional diet based on refined carbohydrate" was NOT confirmed, according to the daily blood glucose profile
During the 3 month trial, the children grew by a mean of 0.8 cm.
During the unrefined diet, mean weight increased by 0.1 kg, and during the refined diet by 0.3 kg
Compared to 24-hr recalls before the trial, 24-hr recall 6 months after the trial indicated that children had significantly increased the proportion of dietary fiber (by 13.6 g/d), carbohydrate and protein and decreased the amount of fat.

Author Conclusion:

Attention to food type and structure can improve blood glucose control in diabetic children and should provide an acceptable and more rational basis for dietary prescription than one based on carbohydrate quantity alone.

Funding Source:

University/Hospital:

John Radcliff Hospital

Reviewer Comments:

Children were managed on a once-daily injection of insulin ((Monotard and Actrapid), which was altered in response to persistent glycosuria/hypoglucemia
This report lacks a description of some of the essential components of research design: description of recruitment; inclusion and exclusion criteria; discussion of limitations of study
Because this study is completely home based, authors can provide "real world" indications for increasing fiber (clinical significance as well as statistical significance); on the other hand, food intake data is completely dependent on self-report .
A small number of subjects participated in the study

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?		???
	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?	N/A
	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?	???
3.	Were study groups comparable?		N/A
	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?	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?	N/A
	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?	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?	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?	???
	6.5.	Were co-interventions (e.g., ancillary treatments, other therapies) described?	N/A
	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?		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?		???
	8.1.	Were statistical analyses adequately described and the results reported appropriately?	???
	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?		???
	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