EAL

DM: Carbohydrates (2007)

Citation:

Study Design:

Class:

- Click here for explanation of classification scheme.

Quality Rating:

Research Purpose:

To evaluate the effects of a high-carbohydrate, high-fiber (HCHF) diet on glucose control in children with type 1 diabetes.

Inclusion Criteria:

Selected for the study on the basis of compliance (following a "standard" diabetes diet; testing blood glucose at home)
Not hospitalized in ketoacidosis for at least 6 months

Exclusion Criteria:

none given

Description of Study Protocol:

Recruitment

Not provided

Design

Comparison of glycemic control after 10 days of "usual" diabetes diet vs 14 days of a HCHF diet in children with type 1 diabetes

Blinding used (if applicable)

Intervention (if applicable)

After receiving instruction and an individualized daily meal plan, the children followed their usual diabetes diet for a week at home and then were admitted to a GCRC for 3 days and given the same diet. On the third day plasma glucose was measured at intervals from breakfast and lunch baselines for 4 hours. Then the subjects were placed on an HCHF diet for 11 days at home and 3 days in the GCRC with repetition of measurements. No attempt was made to improve diabetic control by increasing exercise or altering insulin doses

Individual meal plans were written for each participant (3-meal, 2-snack/d). For the usual diet, no fiber amount was recommended. For the HCHF diet, 30 g fiber/1000 kcal, in the form of natural foods - vegetables (corn, peas), grains, fruits (berries, apples, raisins), and high fiber crackers (18% of fiber) were recommended.

	Usual diet Mean (range)	HCHF diet Mean (range)
Calories (kcal/d)	2236 (1200-3500)	2333 (1200-3500)
Fiber (g/d)	22 (15-40)	64 (46-106)
Carbohydrate (% of cal)	46 (42-49)	60 (58-63)
Protein (% of cal)	19 (17-22)	17 (15-21)
Fat (% of cal)	35 (30-39)	23 (20-32)

Statistical Analysis

Paired comparison test (difference in blood glucose values between the two study periods)

Data Collection Summary:

Timing of Measurements

10th day after the start of the regular diet (baseline and 30, 60, 90, 120, 180, 240 min after breakfast and after lunch); 14th day after the start of the HCHF diet (same timing of measurements)

Dependent Variables

Plasma glucose (glucose-oxidase technique)

Independent Variables

Calories, macronutrients, fiber

Control Variables

C-peptide (radioimmunoassay technique)

Description of Actual Data Sample:

Initial N: 12 (gender not provided)

Attrition (final N): 12

Age: 10-17 yrs

Ethnicity: not provided

Other relevant demographics:

years with diabetes: 1-12 (mean 5.25 yrs)
mean Hemoglobin in A_1c at start of study: 12.4% (range 10-18.9%)

Anthropometrics: none provided

Location: Primary Children's Medical Center, Salt Lake City, Utah

Summary of Results:

Variables	Usual diet	HCHF diet	Statistical Significance of Group Difference
Fasting blood glucose (mg/dl)	259	231	NS
blood glucose 1 hr postprandial (mg/dl)	352	324	NS

Other Findings

No significant difference between diets in the serial blood glucose levels after the breakfast test meal and after the lunch test meal
No significant change in insulin dose during the study.
C-peptides: virtually undetectable in all except 1 subject
During the HCHF diet
- no significant change in weight (47.34 kg before HCHF diet; 47.45 kg after)
- no change in incidence of hypoglycemic reactions
- average insulin dose unchanged

Author Conclusion:

Institution of a HCHF diet does not significantly improve diabetic control in children with long-standing, relatively poorly controlled diabetes. This form of dietary alteration appears to be of limited application in subjects with type 1 diabetes and very little residual beta-cell function. It appears likely that a child must still be able to produce a significant amount of endogenous insulin for the HCHF diet to be beneficial.

Funding Source:

Government:

GCRC, NIH

Reviewer Comments:

Subjects were selected on the basis of compliance rather than control (but were poorly controlled); thus it is not possible to extrapolate results to newly diagnosed or well-controlled subjects with type 1 diabetes

There is no discussion of the method for calculating calories, macronutrients and fiber.

The length of the study may not be long enough to see improvement

Authors were not able to confirm complete adherence to the prescribed fiber amount at home, and do not indicate that children ate all their foods while on the GCRC.

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?		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?	N/A
	2.3.	Were health, demographics, and other characteristics of subjects described?	???
	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?	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%.)	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?	???
	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?	???
	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?	???
	7.6.	Were other factors accounted for (measured) that could affect outcomes?	???
	7.7.	Were the measurements conducted consistently across groups?	N/A
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?	???
	8.3.	Were statistics reported with levels of significance and/or confidence intervals?	No
	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?		Yes
	9.1.	Is there a discussion of findings?	Yes
	9.2.	Are biases and study limitations identified and discussed?	Yes
10.	Is bias due to study's funding or sponsorship unlikely?		Yes
	10.1.	Were sources of funding and investigators' affiliations described?	Yes
	10.2.	Was the study free from apparent conflict of interest?	Yes