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PDM: Prediabetes (2013)

Citation:

Sakane N, Sato J, Tsushita K, Tsujii S, Kotani K, Tsuzaki K, Tominaga M, Kawazu S, Sato Y, Usui T, Kamae I, Yoshida T, Kiyohara Y, Sato S, Kuzuya H, Japan Diabetes Prevention Program (JDPP) Research Group. Prevention of type 2 diabetes in a primary healthcare setting: Three-year results of lifestyle intervention in Japanese subjects with impaired glucose tolerance. BMC Public Health. 2011; 11(1): 40.

PubMed ID: 21235825
 
Study Design:
Randomized Controlled Trial
Class:
A - Click here for explanation of classification scheme.
Quality Rating:
Positive POSITIVE: See Quality Criteria Checklist below.
Research Purpose:

To test the feasibility and effectiveness of a lifestyle intervention program, carried out in a primary healthcare setting using existing resources, in Japanese subjects with impaired glucose tolerance.

Inclusion Criteria:
  • Impaired glucose tolerances shown by one or more of the following:
    • Fasting plasma glucose (FPG) concentration 5.6mmol per L or more but less than 7.0mmol per L
    • Casual plasma glucose (CPG) concentration 7.8mmol per L or more but less than 11.1mmol per L when blood is drawn within two hours after a meal, or CPG concentration of 6.1mmol per L or more but less than 7.8mmol per L when blood is drawn two hours or more after a meal
    • IGT as indicated by a previous 75g oral glucose tolerance test (OGTT)
  • Aged 30 to 60 years
  • Received health checkups at one of 32 centers.
Exclusion Criteria:
  • Previous diagnosis of diabetes mellitus other than gestational diabetes
  • History of gastrectomy
  • Physical conditions such as ischemic heart disease, heart failure, exercise-induced asthma, and orthopedic problems where exercise was not allowed by a doctor
  • Definitive liver and kidney diseases
  • Autoimmune diseases
  • 69g or more alcohol intake per day
  • Already began lifestyle modifications, such as routine moderate to vigorous exercise.
Description of Study Protocol:

Recruitment

Advertising at 32 health centers.

Design

Randomized controlled trial. 304 participants were randomly assigned to either a lifestyle intervention group or a control group.

Blinding Used

Implied with measurements.

Intervention

  • The goals of intervention were:
    • To reduce initial body weight by 5% in overweight and obese subjects
    • To increase energy expenditure due to leisure time physical activity (LTPA) by 700kcal per week
  • Study nurses administered group and individual sessions, using the guideline, curriculum and educational materials provided by the committee of the study group
    • Group sessions (two to three hours): Four sessions in first six months using slides, videotapes and a booklet on diabetes prevention approaches such as diet and exercise
    • Individual session (20 to 40 minutes) every six months based on self-efficacy, self-monitoring and the transtheoretical model, conducted in person or by telephone
  • Referral to dietitian by study nurse when needed
  •  A 27-page booklet titled "Change Your Lifestyle to Prevent Diabetes"
  • Monthly faxes of cartoons encouraging behavior change
  • The control group received only one group session on a healthy lifestyle and the prevention of diabetes at the baseline. 

Statistical Analysis

  • Means ±SD
  • Unpaired T-test, χ2 test
  • Two-tailed paired T-test to analyze differences within groups between the baseline and year one
  • Survival curves  to estimate the cumulative incidence of diabetes. The difference between the groups in the incidence of diabetes was tested by means of the two-sided log-rank test. 
Data Collection Summary:

Timing of Measurements

  •  Labs: Every six months during year one, annually in years two and three
  • Anthropometric: Every three months during year one, every six months in years two and three.

Dependent Variables

  • 75g OGTTs were conducted biannually during the first year and annually thereafter. Total cholesterol, high-density lipoprotein (HDL)-cholesterol, triglyceride, creatinine, uric acid, aspartate aminotransferase (AST), alanine aminotransferase (ALT), gamma-glutamyltransferase (GGT), HbA1c, plasma glucose and insulin levels were measured at a central laboratory (SRL Co. Ltd., Tokyo, Japan)
  • Pancreatic β cell function and insulin resistance were assessed using the homeostasis model assessment (HOMA-β and HOMA-IR, respectively). An insulin sensitivity index (Matsuda index) was also calculated using insulin and glucose data obtained from 75g OGTTs
  • Anthropometric: Overweight/obese determined using WHO recommendations for Asians
  • Waist circumference was measured at the umbilical level
  • Blood pressure measurements.

Independent Variables

  • Intervention  to reduce initial body weight by 5% and increase energy expenditure due to leisure time physical activity (LTPA) by 700kcal per week
    • Study nurses administered group and individual sessions, using the guideline, curriculum and educational materials provided by the committee of the study group
      • Group sessions (two to three hours): Four sessions in first six months using slides, videotapes and a booklet on diabetes prevention approaches such as diet and exercise
      • Individual session (20 to 40 minutes) every six months based on self-efficacy, self-monitoring and the transtheoretical model, conducted in person or by telephone
    • Referral to dietitian by study nurse when needed
    • A 27-page booklet titled "Change Your Lifestyle to Prevent Diabetes"
    • Monthly faxes of cartoons encouraging behavior change
  • The control group received only one group session on a healthy lifestyle and the prevention of diabetes at the baseline
  • Dietary intake assessed using FFQ (N=122 items) annually.  
Description of Actual Data Sample:
  • Initial N: 304 (150 control, 146 intervention)
  • Attrition (final N): 28% attrition after three years (40 in the control group and 43 in the intervention group)
  • Age: 51±6 control and 51±7 intervention
  • Ethnicity: Asian
  • Other relevant demographics: Male to female numbers similar (76/74 control and 74/74 intervention)
  • Anthropometrics: Proportion of overweight (23.0 or less BMI or less than 27.4; 48.5% and 50.0%, respectively) and obese (BMI 27.4 or more; 18.6% and 18.8%, respectively) people
  • Location: Japan.
Summary of Results:

±Key Findings

 

Baseline and One-year or Three-year Follow-up Data in the Control and Intervention Groups.

 

Parameters Control Group Intervention Group P-valueb 
 

Baselinea

(N=131)

One-Year

(N=131)

Three-years

(N=110)

Baseline

(N=123)

One-Year

(N=123)

Three-year

(N=103)

 At One-year Mark At Three-year Mark
Weight (kg)  63.9±11.7 63.1±11.7* 62.5±11.2* 64.9±12.9 63.5±12.9* 63.1±12.9 0.023 0.069
BMI (kg/m2)  24.5±3.2 24.2±3.1* 24.4±3.3* 24.8±3.6 24.2±3.6* 24.3±3.7* 0.022 0.051
Waist circumference (cm)  84.4±9.4 83.3±8.6* 84.2±9.5 85.9±10.9 84.2±10.5* 84.7±11.9 0.309 0.362
Fasting plasma glucose (mmol per L)  6.1±0.5 5.9±0.6 6.0±0.9 5.9±0.5 5.8±0.6* 6.0±0.8 0.698 0.481
Two-hour plasma glucose (mmol per L)  9.0±0.9 8.3±2.0* 8.5±2.4 9.2±0.9 8.0±2.1* 8.4±2.5* 0.083 0.553
Fasting insulin (pmol per L)  43.8±21.6 44.4±40.8 45.8±23.9 43.2±22.2 44.4±271.2 47.6±36.1 0.861 0.632
Two-hour insulin (pmol per L)  330.6±211.8 308.4±178.8 377.4±280.7 337.8±199.8 342.0±271.2  390.0±374.2 0.413 0.999
Matsuda indexe  4.3±3.5 5.6±3.3 5.3±3.2 4.8±2.3 5.9±3.7* 5.5±3.4* <0.001 <0.001

 Other Findings

  • Diabetes was diagnosed in 27 participants over the three-year period (nine intervention and 18 control)
  • Cumulative incidence of diabetes was 8.2% intervention and 14.8% control
  • Relative risk reduction was 53% with the intervention (95% CI: 0.25 to 1.13) (log-rank test: p=0.097) 
  • While serum HDL cholesterol levels increased after three years, serum triglyceride levels did not change
  • Three-year changes in systolic and diastolic blood pressure were not significant.

 

Author Conclusion:

In conclusion, the present study suggests that lifestyle intervention using existing healthcare resources in communities and workplaces is beneficial in preventing or delaying the development of diabetes in middle-aged Japanese with IGT. General improvements in lifestyle including dietary and exercise habits might be meaningful even if the weight reductions achieved are only modest. The findings have important implications for primary healthcare-based diabetes prevention.

Funding Source:
Government: Ministry of Health, Welfare, and Labour of Japan
Reviewer Comments:
  • Statistical analysis didn't account for clustering by community center in intervention effects
  • Attrition over the the-year intervention was 28%, but appears to be non-differential by treatment group.

 

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? 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? 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
  3.5. 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? ???
  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? 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? 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
  6.8. 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? No
  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? No
  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
  8.5. Were adequate adjustments made for effects of confounding factors that might have affected the outcomes (e.g., multivariate analyses)? N/A
  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