EAL

DM: Prevention of Type 2 Diabetes (2007)

Citation:

Study Design:

Class:

- Click here for explanation of classification scheme.

Quality Rating:

Research Purpose:

The aim of this study was to determine the long-term effect of a lifestyle intervention which targeted diet, physical activity and selected anthropometric and metabolic variables in non-diabetic first-degree relatives of type 2 diabetic patients.

Inclusion Criteria:

Subjects with two first-degree relatives with type 2 diabetes, or one first-degree and at least two second-degree relatives.
Normal blood sample results for liver function tests, electrolytes and hemoglobin.
Medical history free from endocrine and cardiovascular diseases

Exclusion Criteria:

Diagnoses of diabetes mellitus (fasting blood glucose >/= 6.1 mmol/l or 2-h blood glucose >/= 11.1 mmol/l or both)
BMI > 35
Presence of any disease or the use of any medications that affected glucose or lipid metabolism

Description of Study Protocol:

Recruitment

Participants were recruited using questionnaires and advertising.

Design

Participants were allocated to one of three treatment groups using the minimization method: diet group (D), diet and exercise group (DE), and control group (C). Participants in the D and DE group met twice for a group dietary education session at the start of the study. Participants in the DE group also received group discussions about the benefits of physical activity. Both the D and DE group received 10 unnannounced telephone interviews during the first 4 months (every 7-9 days) and these continued less frequently (average of 10 weeks) until 2 years after the start of the study. The control group received a letter informing them that they should continue their normal lifestyle and received the same intervention 1 year later with a lower intensity follow-up (for ethical reasons).

Blinding used (if applicable)

Information not found in article.

Intervention (if applicable)

Diet group (D): Dietary advice was aimed at reducing saturated fat (goal <10% of energy), increasing the intake of MUFAs (goal 10-15%), and of n-3 fatty acids (goal 1% of energy). Increasing intake of fruits and vegetables as well as dietary fiber. Increase the intake of low glycemic index (GI) foods and reduce the intake of high GI foods.

Diet and exercise group (DE): This group received the same dietary intervention as the Diet group. In addition, a group discussion was included about the benefits of physical activity, especially on glucose metabolism. The goal was to increase physical activities for at least 30 minutes, four to five times per week.

Statistical Analysis

Group sizes determined by power calculations. One-way analysis of variance with post-hoc Tukey's test was used for comparisons of changes between groups at 1 year. A two-tailed t-test was used to compare groups D and DE at 2-year follow-up. Wilcoxon signed rank test was used for non-parametric comparisons.

Data Collection Summary:

Timing of Measurements

Baseline: OGTT, FFQ, fasting blood sample, Minnesota leisure time physical activity questionnaire, height, weight, waist and hip circumference
4-month: Height, weight, waist and hip circumference
Intensive follow-up (every 8 days for first 4 months and every 10 weeks for rest of study): D group: 24-hour recall by telephone interview, DE group: 24-hour recall and 72-h physical activity recall by telephone interview
1 Year: Fasting blood sample, height, weight, waist and hip circumference, FFQ, and Minnesota leisure time physical activity questionnaire
2 Years: OGTT, fasting blood sample, height, weight, waist and hip circumference, FFQ, and Minnesota leisure time physical activity questionnaire

Dependent Variables

Metabolic measures (2-hour glucose measured by OGTT, fasting insulin and glucose, cholesterol levels)
Anthropometrics (height, weight, waist and hip circumference)

Independent Variables

Diet, Diet and Exercise or Control group, measured through semi-quantitative FFQ
Physical activity measured with Minnesota leisure time physical activity questionnaire

Control Variables

Description of Actual Data Sample:

Initial N: 100 screened, 77 men and women randomized to groups.

Attrition (final N): 68 participants at 1 year, 64 participants at 2-year follow-up

Age: 25-55 years of age

Ethnicity: unknown

Other relevant demographics:

Treatment groups were comparable at baseline regarding diet composition, anthropometric and metabolic variables, but large variations were observed in baseline physical activity level within all three groups. Differences were not statistically significant.

Physical activity (min/week) [median (range)]

Group D= 230 (0-520)

Group DE= 90 (0-610)

Group C= 215 (0-1110)

Anthropometrics:

At Baseline (mean)-

	D group	DE	C
BMI	25.0	26.1	26.1
Body weight (kg)	78.7	79.8	78.0

Location: Sweden

Summary of Results:

The 2-year follow-up showed sustained dietary change within groups D and DE although with diminishing strength when compared ot data at year 1. AFter 2 years, there were no overall changes from baseline in the amount of time spent on physical activity in any of the groups. However, looking at those who were "inactive" at baseline (<120 min of PA/week), a significant increase from baseline was observed within group DE. The decrease in body weight in group dE after 1 year was sustained within the group at 2 years. Fasting insulin was also reduced within this group, and compared to group D (p - 0.025). Two-hour insulin was unchanged during the 2 eyar period in all groups. Total cholesterol, LDL cholesterol and the ration of LDL to HDL cholesterol were reduced wtihin group D, and compared to DE (p = 0.022, 0.009, 0.035, respectively).

	Change D (n=24)	Change DE (n=24)	D vs DE p
Energy (kcal)	-330	-220	0.564
Fat (E%)	-4.9	-1.6	0.068
SFA (E%)	-4.5	-2.0	0.034
Fiber (g/1000 kcal)	3.1	2.1	0.373
Physical activity (min/week)	35	10	--
Body Weight (kg)	-0.08	-1.9	0.114
2 h blood glucose at OGTT (mmol/l)	0.47	-0.00	0.216
Total cholesterol (mmol/l)	-0.28	0.13	0.022
HDL cholesterol (mmol/l)	-0.01	0.01	0.795
LDL cholesterol (mmol/l)	-0.25	0.16	0.009
LDL/HDL cholesterol	-0.18	0.12	0/035

Other Findings

Following 1 year of intervention, groups D and DE showed significant changes from baseline in most variables measuring dietary adherance. Some nutrition composition changes were significant when compared the control group. These included % fat (p = 0.48) and MUFA of calories (p = 0.039) for DE vs. C and % SFA of calories and dietary fiber for D vs. C and DE vs. C.

Body weight changes (kg) were -0.45 for group D, -2.16 for group DE, and 0.52 for group C. There was a significant difference between DE and C groups (p = 0.029).

Fasting glucose in groups D and DE was reduced within groups, but no between group differences were observed. Fasting insulin did not change in any of the groups. Compared to group C, group DE showed a significant increase in HDL, while group D decreased the ratio of LDL to HDL cholesterol.

Author Conclusion:

Positive changes in lifestyle were achieved after 1 year and maintained after 2 years in a non-diabetic population at risk of type 2 diabetes. Sustained improvements were shown in lipid variables in the diet group and in fasting insulin in the diet and exercise group. Multiple dietary changes were sustained 2 years after the initiation of the intervention.

Funding Source:

Reviewer Comments:

Good study showing sustained lifestyle changes after 2 years. Take note that baseline physical activity levels (min/week) varied widely between groups. The groups were matched for a number of variables at baseline but not lifestyle data which included physical activity. The number of inactive individuals tended to be larger in the diet and exercise group compared to the two other groups.

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")?	Yes
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?		???
	5.1.	In intervention study, were subjects, clinicians/practitioners, and investigators blinded to treatment group, as appropriate?	???
	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?	Yes
	6.6.	Were extra or unplanned treatments described?	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
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)?	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
	8.7.	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