EAL

DM: Prevention of Type 2 Diabetes (2007)

Citation:

Study Design:

Class:

- Click here for explanation of classification scheme.

Quality Rating:

Research Purpose:

Researchers investigated the association between the intensity and duration of leisure-time physical activities, and directly assessed cardiorespirator fitness and incident cases of NIDDM that were determined from an oral glucose tolerance test in a population-based sample of middle-aged, eastern Finnish men.

Inclusion Criteria:

1. Participants in the Kuopio (Finland) Ischemic Heart Disease Risk Factor Study

2. Complete information on physical activity, blood glucose levels, and all other risk factors.

Exclusion Criteria:

1. Baseline data:

a. taking oral hypoglycemic medications for diabetes

b. fasting blood glucose >=120 mg/dL.

2. Missing data

3. Serious health problem

Description of Study Protocol:

Recruitment: Subjects were participants in the Kuopio (Finland) Ischemic Heart Disease Risk Factor Study, which was designed to investigate previously unestablished risk factors for ischemic heart disease, carotid atherosclerosis, and other related outcomes in a population-based sample of eastern Finnish men.

Design: Cohort Study

Blinding Used: not applicable

Intervention: not applicable.

Statistical Analysis: The association between the total durations of higher- and lower- intensity leisure-time physical activities, cardiorespiratory fitness, potential risk factors, and NIDDM was assessed by multivariate logistic regression.

Data Collection Summary:

Timing of measurements:

Baseline assessment of physical activity. Diagnosis of type 2 diabetes at baseline and 4 yr follow-up. Cardiorespiratory fitness at baseline. Assessment of risk factors at baseline and ultrasonographic exam of carotid arteries.

Dependent variables:

Diagnosis of NIDDM determined from 75 g glucose, OGTT using the criteria for fasting blood glucose >120 mg/dL or 2-hr >180 mg/dL.

Independent variables:

Frequency, intensity and duration of 12-month leisure-time physical activity history modified from the Minnesota Leisure Time Physical Activity Questionnaire with 15 of the most common activities of middle-aged Finnish men; with metabolic units (MET’s) were assigned for each type of activity according to the reported intensity.
Directly assessed cardiorespiratory fitness measured directly from respiratory gas exchange during a maximal, symptom-limited exercise tolerance test on a bicycle ergometer and reported in quartiles.

Control Variables:

Potential risk factors (baseline blood glucose, BMI, waist-hip ratio, blood pressure, lipid levels, alcohol consumption, parental history of diabetes

Description of Actual Data Sample:

Initial N: Of the 3433 eligible men, 198 were not included because of death, serious disease, or migration from the area. 82.9% agreed to participate in the study. Of the 1229 participants eligible for the study at 4-yr follow-up, only 1038 participated in follow-up; 52 had died, were suffering from severe illness and 139 couldn’t be contacted or refused follow-up.

Attrition (Final N): Complete data was available on 897 men.

Age: NIDDM mean age 52.2 +/- 6.2 years, normal mean age 51.2 +/- 6.66 years

Ethnicity: Finnish men

Other relevant demographics: none

Anthropometrics:

Subject with NIDDM - BMI = 30.15 and Waist-Hip ratio = 0.98

Subjects with no NIDDM - BMI = 26.50 and Waist-Hip ratio = 0.94

Location: Finland

Summary of Results:

Other Findings

At 4-yr follow-up, 46 men had been diagnosed with type 2 diabetes mellitus.

After adjustment for age, baseline glucose values, BMI, serum TG, family history of diabetes, and alcohol consumption, moderately intense physical activity (>=5.5 METs) for >=40 minutes in duration/week were associated with a decreased risk for type 2 diabetes mellitus (Odds ratio, 0.44, 95% CI, 0.22 to 0.89). Activities with intensity less than 5.5 METs, regardless of duration, were not protective.

Cardiorespiratory fitness > 31 ml of oxygen/kg/minute were protective against type 2 diabetes mellitus. (OR, 0.26, 95% CI, 0.08-0.82)

Men at increased risk for type 2 diabetes mellitus because of being overweight, hypertensive and with a family history of diabetes, who engaged in moderately intense physical activity >40 min/wk decreased the risk of type 2 diabetes mellitus by 64% compared with men who did not participate in physical activity.

Author Conclusion:

After adjustment for age, baseline glucose and known risk factors, physical activities with an intensity >=5.5 METS and a duration >=40 minutes/week protected against the development of type 2 diabetes mellitus. These protective effects were even more pronounced in a subgroup of men who were at high risk for the development of the disease.

Funding Source:

Government:	NHLBI, Finnish Ministry of Education
University/Hospital:	Academy of Finland

Reviewer Comments:

Well-defined assessment of physical activity—frequency, duration and intensity. Even men who were obese were able to reduce the risk of type 2 diabetes mellitus with regular physical activity.

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)	N/A
	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.)	No
	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?	Yes
	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?	Yes
	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?	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.)	N/A
	5.3.	In cohort study or cross-sectional study, were measurements of outcomes and risk factors blinded?	No
	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?	N/A
	6.2.	In observational study, were interventions, study settings, and clinicians/provider described?	Yes
	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?	N/A
	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)?	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?	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