EAL

DM: Prevention of Type 2 Diabetes (2007)

Citation:

Watanabe M, Yokotsuka M, Yamaoka K, Tango T. Randomized controlled trial of a new dietary education program to prevent type 2 diabetes in a high-risk group of Japanese male workers. Diabetes Care 2003:3209-3214.

PubMed ID: 14633803

Study Design:

Randomized controlled trial

Class:

A - Click here for explanation of classification scheme.

Quality Rating:

NEUTRAL: See Quality Criteria Checklist below.

Research Purpose:

To assess the effectiveness of a new dietary education (NDE) program in reducing plasma glucose (PG) levels in Japanese male workers at high risk for type 2 diabetes through a randomized controlled trial and to implement an evidence-based nutritional program.

Inclusion Criteria:

male workers at high risk for type 2 diabetes
aged 35-70 years
living in a metropolitan area of Tokyo, Japan
borderline individuals were considered high risk which was identified as a one-hour PG≥10 mmol/L and a fasting blood glucose (FBG) of≥6.1mmol/L and<7.0 mmol/L and a two-hour PG≥7.8 mmol/L and<11.1 mmol/L

Exclusion Criteria:

Subjects taking hypoglycemic agents, cholesterol-lowering drugs or antihypertensive drugs were excluded
Those subjects who refused to participate in the dietary questionnaire survey were excluded

Description of Study Protocol:

Recruitment

Subjects were recruited during an annual health checkup in a health examination center located in the center of Tokyo from February 2000 to January 2001.

Design

Subjects were recruited to either the NDE or the control group after the initial examintation which included anthropometrics, blood pressure measurements and an oral glucose tolerance test.
Each subject in the NDE group recieved individualized counseling using a booklet explaining the concepts of the NDE. The NDE provided information on dietary practices revealed by the semiquantitative food frequency questionnaire (FFQW65) that included 65 food items for each meal, motivational practices to improve dietary practices and help in behavior modification.
Counseling aimed to reduce total energy intake and to adopt habits appropriate for preventon of diabetes.
Dietary counseling was tailored to each subject on the basis of the FFQW65 corresponding to the recommended dietary allowances (RDA).

Blinding used (if applicable)

Group assignment was blinded to staff and subjects.

Intervention (if applicable)

Each subject in the NDE group received individualized counseling using a booklet explaining the concepts of the NDE.

Statistical Analysis

Subjects were randomly assigned to the NDE group or the control group by the use of a randomization list.
Difference between groups for baseline characteristics of the subjects who completed the trial were assessed by the Student's t test and Wilcoxon's rank-sum test.
Outcome measures were compared using ANCOVA by adjusting for baseline values.
Spearman's correlation coefficient was used for examining the relationship between the percent changes in glucose values (fasting, one-hour PG and two-hour PG) and the change in the absolute value of the "overintake/underintake fraction" by the NDE group and control group.
Subjects who dropped out before the end of the one-year intervention period were not included in the main analysis.
An intent-to-treat approach was used in which a binary outcome measure of "reduced/not reduced" that applied to all randomized subjects was used, where reduction was defined as "percent change of glucose level > 10 percent" and the subjects without data were assigned to "not reduced."
For each of the glucose values, the odds ratio (crude and adjusted for baseline value) of reduction in the NDE group was estimated by logistic regression models for the subjects used in the main analysis and for all randomized subjects.
All tests for significance were two-sided with a five percent significance level.

Data Collection Summary:

Timing of Measurements

Nutrition counseling was given after initial enrollment in the study. During the second part of the study four items were mailed to the NDE subjects in addition to a letter encouraging the subject to improve dietary habits:

1) self-administered checklist consisting of 10 items that assessed dietary intake;

2) information related to improving dietary behavior;

3) examples of menus corresponding to the subject's RDA; and

4) information to confirm the necessity of blood glucose control.

Dependent Variables

Percent change from baseline in two-hour PG values one year after initiation of dietary education
Change from baseline in the absolute value of "overintake/underintake fraction" for total energy. This was measured as [(actual total energy intake/RDA) -1] X 100(%).

Independent Variables

NDE; energy intake for each meal was estimated according to food groups corresponding to the Japanese Diabetes Society (JDS) food exchange booklet.

Control Variables

Smoking status was used as a covariate.

Description of Actual Data Sample:

Initial N: 173 subjects (86 NDE group, 87 control)

Attrition (final N): 156 (90.2 percent) completed the one-year follow-up (79 NDE group, 77 control)

Age: NDE group 55.2 ± 7.4, control 54.9 ± 6.7 years

Ethnicity: Japanese

Other relevant demographics:

Smoking status: NDE group 22 (28 %) yes, Control group: 30 (39%) yes.

Anthropometrics

At baseline characteristics did not differ statistically between groups except for FPG (P<0.05) and two-hour PG (P<0.01).

Location:

Tokyo, Japan

Summary of Results:

Percent changes in two-hour PG and changes from baseline in the absolute value of "overintake/underintake fraction" for total energy intake one year after initiation of dietary education in the NDE group and the control group.

Variables	NDE grop	Control group	Adjusted difference between the groups
			Mean	95% CI	Two-tailed P
n	79	77
Percent change in plasma glucose (PG) (%)
Fasting	-0.5±0.9	2.2±0.9	-1.8	-4.2 to 0.6	0.153
1-hour PG	-5.2±2.6	-3.3±2.3	-3.7	-9.9 to 2.5	0.242
2-hour PG	-8.2±1.9	11.2±3.0	-15.2	-8.4 to -22.0	<0.001
Change from baseline in the absolute value of "overintake/underintake fraction" for total energy intake (%)
Breakfast	0.4±1.5	-2.1±0.9	2.6	-0.7 to 5.8	0.126
Lunch	0.4±1.1	1.0±1.2	-0.5	-3.8 to 2.7	0.746
Dinner	-3.0±4.1	11.7±3.7	-15.3	-24.6 to -6.0	0.002
Daily	-1.8±1.5	4.0±1.4	-6.0	-9.8 to -2.2	0.002

Other Findings

The NDE group had a significantly lower total energy intake at dinner and daily than the control group. The NDE group had a decreased two-hour PG after one year, whereas that value was increased in the control group.

Author Conclusion:

An increase in two-hour PG can be prevented by an individualized counseling and diabetes education program using the FFQW65 for male workers at high risk for type 2 diabetes. The two-hour PG was reduced by approximately 15 percent (adjusted) compared to the control group.

Funding Source:

Reviewer Comments:

The time frame of one year is short to show a difference in incidence of type 2 diabetes between NDE and the control group.
Only male Japanese workers were enrolled in the study.
The definition of high-risk may not have been as stringent as that of the impaired gluscoes tolerance (IGT) definition.
Physical exercise was not recorded
Statistically significant differences between groups at baseline

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
	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
	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
	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
	4.	Is the intervention or procedure feasible? (NA for some epidemiological studies)	Yes

Validity Questions
	1.	Was the research question clearly stated?	Yes
1.	Was the research question clearly stated?		Yes
	1.1.	Was (were) the specific intervention(s) or procedure(s) [independent variable(s)] identified?	Yes
	1.1.	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
	1.2.	Was (were) the outcome(s) [dependent variable(s)] clearly indicated?	Yes
	1.3.	Were the target population and setting specified?	Yes
	1.3.	Were the target population and setting specified?	Yes
	2.	Was the selection of study subjects/patients free from bias?	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
	2.1.	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
	2.2.	Were criteria applied equally to all study groups?	Yes
	2.3.	Were health, demographics, and other characteristics of subjects described?	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
	2.4.	Were the subjects/patients a representative sample of the relevant population?	No
	3.	Were study groups comparable?	???
3.	Were study groups comparable?		???
	3.1.	Was the method of assigning subjects/patients to groups described and unbiased? (Method of randomization identified if RCT)	Yes
	3.1.	Was the method of assigning subjects/patients to groups described and unbiased? (Method of randomization identified if RCT)	Yes
	3.2.	Were distribution of disease status, prognostic factors, and other factors (e.g., demographics) similar across study groups at baseline?	No
	3.2.	Were distribution of disease status, prognostic factors, and other factors (e.g., demographics) similar across study groups at baseline?	No
	3.3.	Were concurrent controls or comparisons used? (Concurrent preferred over historical control or comparison groups.)	Yes
	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
	3.4.	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
	3.5.	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
	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.	Was method of handling withdrawals described?		Yes
	4.1.	Were follow-up methods described and the same for all groups?	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
	4.2.	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
	4.3.	Were all enrolled subjects/patients (in the original sample) accounted for?	Yes
	4.4.	Were reasons for withdrawals similar across groups?	Yes
	4.4.	Were reasons for withdrawals similar across groups?	Yes
	4.5.	If diagnostic test, was decision to perform reference test not dependent on results of test under study?	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.	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?	Yes
	5.1.	In intervention study, were subjects, clinicians/practitioners, and investigators blinded to treatment group, as appropriate?	Yes
	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
	5.2.	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
	5.3.	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
	5.4.	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
	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?	???
6.	Were intervention/therapeutic regimens/exposure factor or procedure and any comparison(s) described in detail? Were interveningfactors described?		???
	6.1.	In RCT or other intervention trial, were protocols described for all regimens studied?	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
	6.2.	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?	???
	6.3.	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?	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?	N/A
	6.5.	Were co-interventions (e.g., ancillary treatments, other therapies) described?	N/A
	6.6.	Were extra or unplanned treatments described?	N/A
	6.6.	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
	6.7.	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?	Yes
	6.8.	In diagnostic study, were details of test administration and replication sufficient?	Yes
	7.	Were outcomes clearly defined and the measurements valid and reliable?	Yes
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
	7.1.	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
	7.2.	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
	7.3.	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
	7.4.	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
	7.5.	Was the measurement of effect at an appropriate level of precision?	Yes
	7.6.	Were other factors accounted for (measured) that could affect outcomes?	???
	7.6.	Were other factors accounted for (measured) that could affect outcomes?	???
	7.7.	Were the measurements conducted consistently across groups?	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.	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
	8.1.	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
	8.2.	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
	8.3.	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
	8.4.	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
	8.5.	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
	8.6.	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
	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.	Are conclusions supported by results with biases and limitations taken into consideration?		Yes
	9.1.	Is there a discussion of findings?	Yes
	9.1.	Is there a discussion of findings?	Yes
	9.2.	Are biases and study limitations identified and discussed?	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.	Is bias due to study's funding or sponsorship unlikely?		Yes
	10.1.	Were sources of funding and investigators' affiliations described?	Yes
	10.1.	Were sources of funding and investigators' affiliations described?	Yes
	10.2.	Was the study free from apparent conflict of interest?	Yes
	10.2.	Was the study free from apparent conflict of interest?	Yes