EAL

DM: Prevention and Treatment of CVD (2007)

Citation:

Study Design:

Class:

- Click here for explanation of classification scheme.

Quality Rating:

Research Purpose:

To evaluate the effect of diet therapy on lipid peroxidation in patients with type 2 diabetes mellitus.

Inclusion Criteria:

new cases: type elapsed since diagnosis < 1 year, or patients never previously managed with diet therapy
fasting plasma glucose above 126 mg/dl on at least 3 days

Exclusion Criteria:

on a special diet
taking supplements of vitamins C, E, or beta-carotenoids
endrocrine, liver, or kidney disorders

Description of Study Protocol:

Recruitment : chosen from patients attending a diabetes center

Design : Nonrandomized trial with 8-week dietary intervention period

Blinding used (if applicable): not applicable

Intervention (if applicable)

patients given a diabetic diet comprised of 50-60% CHO, 10-15% protein, 20-30% fat, and 35 g fiber in 3 main meals, two snacks, and one supper
calories planned for weight maintenance

Statistical Analysis

quantitative data expressed as means and SEM
means with normal distribution and those without normal distribution were tested statistically using paired t test and Wilcoxon test, respectively
power analysis resulted in minimum sample size of 10 needed

Data Collection Summary:

Timing of Measurements: dietary data, anthropometric measures collected at the beginning of the study and after 8 weeks of dietary intervention

Dependent Variables

total cholesterol
triacylglycerols
fasting blood sugar
HDL
LDL
lipid peroxidation using the method of Satoh: concentration of serum malondialdehyde (MDA) measured using thiobarbituric acid reaction substances
HbA1c

Independent Variables

patients given a diabetic diet comprised of 50-60% CHO, 10-15% protein, 20-30% fat, and 35 g fiber in 3 main meals, two snacks, and one supper
calories planned for weight maintenance
dietary compliance assessed via 3-day food record during the first week of the dietary intervention period
physical activities and medication were not changed during the study

Control Variables

Description of Actual Data Sample:

Initial N: 15; 9 women, 6 men

Attrition (final N): 15

Age: 35-70y, mean 57.4 +/- 1.5 years

Ethnicity: not specified

Other relevant demographics:

Anthropometrics

Weight 66.0±1.9 kg
BMI 26.3±0.6

Location: Iran

Summary of Results:

Variables	Week 0	Week 8	P Value
Weight, kg	66.0±1.9	66.2±2	NS
BMI	26.3±0.6	26.4±0.6	NS
Total Cholesterol, mg/dl	238±7.5	230.9±7.1	NS
Triacylglycerols, mg/dl	153±7.7	146.8±8.4	NS
LDL, mg/dl	170.6±7.8	164±7	NS
HDL, mg/dl	38.0±1.7	40.0±1.2	NS
fasting blood sugar, mg/dl	203.6±6.3	153.5±6.0	<0.001
HbA1c, %	11.6±0.6	9.07±0.5	<0.001
MDA, nmol/ml	5.73±0.18	4.35±0.13	<0.001
kcal/day	1745±58.1	1666.3±58.5	NS
protein, g/day	61±2.5	64.8±3.4	0.03
fat, g/day	40.2±1.7	36.5±1.6	0.01
carbohydrate, g/day	279±14.8	251±10.4	NS
fiber, g/day	25.6±1.4	32.7±1.1	0.001

Other Findings

Author Conclusion:

A significant reduction in the serum levels of MDA are likely due to the reduction of blood glucose levels. Glycemic optimization, through diet and independent of weight and blood lipid profile, seems the most effective factor in reducing the process of lipid peroxidation in type 2 diabetes. This may have preventive implications for such diabetic complications as atherosclerosis.

Funding Source:

Reviewer Comments:

Power analysis done. Authors note that 87% of patients were taking medications, but these were constant throughout the study and were less likely to be a confounder.

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?		Yes
	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?	Yes
	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?	Yes
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?	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
	5.3.	In cohort study or cross-sectional study, were measurements of outcomes and risk factors blinded?	Yes
	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?	N/A
	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?	N/A
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)?	N/A
	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?	Yes
9.	Are conclusions supported by results with biases and limitations taken into consideration?		Yes
	9.1.	Is there a discussion of findings?	Yes
	9.2.	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