EAL

Diabetes and Carbohydrates

Citation:

Study Design:

Class:

- Click here for explanation of classification scheme.

Quality Rating:

Research Purpose:

To examine the long-term effects of altering meal frequency on measures of glucose and lipid metabolism in type 2 diabetics.

Inclusion Criteria:

Diagnosis of type 2 diabetes mellitus or persistently impaired glucose tolerance.

Exclusion Criteria:

None specifically mentioned.

Description of Study Protocol:

Recruitment

Recruitment methods not defined.

Design: Randomized Crossover Trial. Subjects were randomly assigned to a 4-wk trial of either 3 meals/d or 9 meals/d and then crossed over to the other study diet. Regimen were isoenergetic, based on a prestudy 4-day food record. Subjects were free-living and selected their own food. Researchers maintained weekly contact with participants to help maintain compliance.

Intervention

1) 3-meal/d diet:

Energy distribution: breakfast, 25%, lunch, 25%, dinner, ~50%, and 1 snack of ~150 kcal or 2 snacks of ~75 kcal to be consumed at lib.

2) 9-meal/d diet:

Meals/snacks 1-2-hr apart.

Energy distribution: Early a.m.: 8.3%, breakfast, 8.3%, min-morning, 8.3%, lunch: 8.3%, mid-p.m., 8.3%, late p.m.: 8.3%, dinner: 16.6%, late p.m., 16.6%.

Subjects received diet instruction and completed a 3-day diet record at the end 2-wk and 4-wk of each study diet

Method of Randomization: not mentioned

Blinding Used: not used

Statistical Analysis:

areas under the glucose, insulin, triglyceride, and insuline/glucose curves were calculated using the trapezoidal rule
Body weight, blood pressure and the lipid, lipoprotein, and apolipoprotein values were tested for the effect of treatment (3 or 9 meals/day), time (week of measurement), and the order of treatment with a repeated measures analysis of variance
Triglyceride, glucose, insulin, and insulin-to-glucose curves obtained during the glucose tolerance test were tested for the effect of treatment, time, and order, using multiple analysis of variance.
Student's paired t test was used to compare dietary intake, 24-h urine C-peptide and creatinine, and HbA1C values obtained on the 3- and 9-meal regimens.

Data Collection Summary:

Timing of Measurements

3-day food records completed at the end of the 2nd and 4th weeks on each diet.

Fasting blood samples taken day 1 and 4 before the study and at the end of wk 2, 3, and 4 of each study period.

24-hr urine was taken during wk 4 and blood taken for HbA1c at the end of each diet period.

Dependent Variables

total cholesterol
LDL cholesterol
HDL cholesterol
triglycerides
apolipoprotein B
HbA1C
Fasting blood glucose
Serum insulin
24-hour urine C-peptide
24-hour urine creatinine

Independent Variables

3 meal/day or 9 meal/day diet for 4 week periods
Adherence to the meal frequency was assessed from self-reported records of the number of meals and snacks consumed each day.

Control Variables

use of hypoglycemic agents
diabetes diagnosis v. persistent impairment of glucose tolerance

Description of Actual Data Sample:

Initial N: 17 subjects initially recruited

Attrition (final N): 13 (4 men and 9 women). Of these 11 had diagnosed diabetes and 2 had persistent impaired glucose tolerance, as defined by impaired response to a glucose load on at least two occasions. Ten subjects were treated with diet alone and three subjects were on diet plus hypoglycemic agents.

Age: 46 to 70

Ethnicity: not stated

Other relevant demographics:

Anthropmetrics: BMI 29.9±4.2

Location: New Zealand

Summary of Results:

Other Findings

Nutrient, blood and urine measurements: Nutrient intakes and all measures of carbohydrate and lipid metabolism were similar on the 3 and 9 meal/d regimes.

Meals per day: 3.2±0.3 and 8.2±0.5 meals/d. Only fat intake was significantly different from baseline and that was true for both diets.

Body weight: Small decreases in weight on both experimental diets (P<0.002).

3-meal/d: 79.03±8.16 to 78.91±7.91 kg
9-meal/d: 79.438.27 to 79.00±8.47 kg

Repeated measures ANOVA indicated that there were no significant differences in any of the measures of lipid, glucose, insulin, HbA1c by the number of meals/d.

Author Conclusion:

This study indicates that there is little benefit in a practical setting of recommending frequent small meals for persons with type 2 diabetes mellitus. Self-blood glucose monitoring is recommended for individuals to evaluate if meal frequency impacts blood glucose control.

It is possible that the small sample size was not sufficient to detect significant changes.

Funding Source:

University/Hospital:

Univeristy of Otago (Dunedin New Zealand)

Reviewer Comments:

The insulin response to a 75-g glucose load differed somewhat. Insulin remained high between 1 and 2-hr during the 9-meal/d study compared to the 3-meal/d study. The differences were not significant but this may be because of the small sample size.

In the 9-meal/d diet, the distribution of calories among meals and snacks were similar except for the evening meal and snack, which was twice the amount of calories. A more realistic distribution would be twice the amount of kcal for meals compared to snacks.

No power calculations were completed to assure that the negative results were reliable. The sample size was small and the inclusion criteria were few in number.

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?	No
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?		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?		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%.)	???
	4.3.	Were all enrolled subjects/patients (in the original sample) accounted for?	No
	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
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.)	???
	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?	Yes
	6.5.	Were co-interventions (e.g., ancillary treatments, other therapies) described?	Yes
	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)?	No
	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?		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?	No
	10.2.	Was the study free from apparent conflict of interest?	Yes