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NC: Diabetes Management (2007)

Citation:

Study Design:

Class:

- Click here for explanation of classification scheme.

Quality Rating:

Research Purpose:

To test a lifestyle intervention (aimed at diabetes type 2 prevention) that is feasible in primary health care.
This paper describes the lifestyle intervention program, the changes in dietary habits and exercise behavior that was achieved during the first year and the maintenance of these changes after 3 years.
The efficacy of the intervention will be evaluated by measures of body weight, plasma glucose, and lipids.

Inclusion Criteria:

Age 40-64 years at screening
Body mass index (BMI) >25 kg/m²at screening
The mean value of two 75-gram oral glucose tolerance tests (OGTTs) in the impaired glucose tolerance range based on World Health Organization criteria

Exclusion Criteria:

not discussed

Description of Study Protocol:

Recruitment

Local advertisements
Subjects may have been identified in earlier epidemiological surveys

Design

1 year intervention RCT with 3 year follow-up

Blinding used (if applicable)

Not used

Intervention (if applicable)

Subjects randomized to either intervention group or usual care group
Intervention group received structured dietary and exercise consultation which was more intensive the first year; usual care group received general information regarding lifestyle and diabetes risk

Statistical Analysis

Differences between the intervention and usual care group were tested with Student's t test, Mann-Whitney nonparametric test, X² test, or ANCOVA adjusting for baseline value, using SAS software version 8.2

Data Collection Summary:

Timing of Measurements

Baseline and annually

Dependent Variables

Glucose levels as measured by plasma, serum or capillary blood
Serum total cholesterol, HDL cholesterol, and triglycerides
A1C analyzed using Bayer DCA2000 Analyzer
Assessment of dietary intake as measured by 3 day food records
Physical activity as measured by a validated questionnaire

Independent Variables

Diet instruction and exercise instruction

Control Variables

Description of Actual Data Sample:

Initial N: 522 (172 males)

Attrition (final N): 506 at 1 year/ 434 at 3 years

Mean age: 55 ± 7 years

Ethnicity: Finnish

Other relevant demographics: Regarding schooling: 40% had 0-9 years; 27% had 10-12 years/ 33% had =/>13 years

Anthropometrics: The two study groups had similiar baseline characteristics that could be identified as diabetes risk factors which included BMI, first-degree relatives with diabetes, dietary intake, exercise and metabolic measures.

Location: 5 study centers in Finland

Summary of Results:

**Change in measures from baseline to 1 year**
Variables	Intervention Group n=256	Control group n=250	Statistical Significance of Group Difference
Total kcalories/ day	-247 ± 428	-108 ± 464	0.0001
Moderate -to-vigorous activity (minutes/wk)	49 (-41 to 140)	14 (-47 to 90)	0.0073
Weight (kg)	-4.5 ± 5.0	-1.0 ± 3.7	<0.0001
Body Mass Index (kg/m²)	-1.6 ± 1.8	-0.4 ± 1.3	<0.0001
Fasting plasma glucose (mmol/l)	-0.2 ± 0.7	-0.0 ± 0.7	<0.0001
2-hour plasma glucose (mmol/l)	-0.9 ± 1.9	-0.3 ± 2.2	0.001
Total serum cholesterol (mmol/l)	-0.1 ± 0.7	-0.1 ± 0.7	0.5097
Serum triglycerides (mmol/l)	-0.2 ± 0.6	-0.0 ± 0.7	<0.0001

**Change in measures from baseline to 3 year**
Variables	Intervention Group n=231	Control group n=203	Statistical Significance of Group Difference
Total kcalories/ day	-204 ± 489	-97 ± 458	0.0067
Moderate -to-vigorous activity (minutes/wk)	61 (-33 to 168)	6 (-91 to 104)	0.0057
Weight (kg)	-3.5 ± 5.1	-0.9 ± 5.4	<0.0001
Body Mass Index (kg/m²)	-1.3 ± 1.9	-0.3 ± 2.0	<0.0001
Fasting plasma glucose (mmol/l)	-0.0 ± 0.7	0.1 ± 0.7	0.0664
2-hour plasma glucose (mmol/l)	-0.5± 2.4	-0.1 ± 2.2	0.0664
Total serum cholesterol (mmol/l)	-0.1 ± 0.9	0.1 ± 0.8	0.0712
Serum triglycerides (mmol/l)	-0.1 ± 0.6	-0.0 ± 0.8	0.024

Other Findings

Author Conclusion:

The main finding in the DPS was that nonpharmacologic lifestyle intervention of people at high risk for diabetes does prevent or at least postpone the onset of type 2 diabetes.

Funding Source:

Reviewer Comments:

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?		???
	4.1.	Were follow-up methods described and the same for all groups?	???
	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%.)	No
	4.3.	Were all enrolled subjects/patients (in the original sample) accounted for?	No
	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?		???
	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.)	???
	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?	No
	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)?	???
	8.5.	Were adequate adjustments made for effects of confounding factors that might have affected the outcomes (e.g., multivariate analyses)?	???
	8.6.	Was clinical significance as well as statistical significance reported?	???
	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