EAL

Diabetes and Physical Activity

Citation:

Study Design:

Class:

- Click here for explanation of classification scheme.

Quality Rating:

Research Purpose:

To evaluate the effects of walking combined with diet therapy (1,000 - 1,600 kcal/day) on insulin sensitivity in obese non-insulin dependent diabetes mellitus patients.

Inclusion Criteria:

diagnosis of diabetes 1 yr prior to study using the WHI criteria with 75 g glucose load
treatment of diabetes with diet
good glycemic control

Exclusion Criteria:

Diabetes related complications
Medications for diabetes
Prior participation in athletics or regular physical activity

Description of Study Protocol:

Recruitment

Methods not specified.

Design: Randomized Controlled Trial

Blinding Used (if applicable): not possible - lab tests.

Intervention (if applicable):

Subjects were hospitalized for 6-8 wks and ingested a diet reduced by 1000 kcal than usual intake (1,000 to 1,600 kcal, 54-58% CHO, 17-20% protein, 25-26% fat). The Diet Alone group continued with usual walking pattern, the Diet and Exercise group made 10,000 steps/day on flat surface.

Statistical Analysis:

Statistical analyses performed by paired or unpaired Student's t tests. Repeated measures ANOVA was used to compare changes in metabolic clearance rate in the 2 groups. Multiple regression was performed to determine which factor, exercise or body weight reduction, correlated with the changes in metabolic clearance rate.

Data Collection Summary:

Timing of Measurements

Glucose clamp procedure performed at an insulin infusion rate of 40 mU • m^-2• min^-1for 120 minutes in the postabsorptive state after an overnight fast and before and after training. Blood samples taken before and at 30, 60, 90 and 120 minutes during the clamp procedure.

Dependent Variables

Weight
Glucose infusion rate
Metabolic clearance rate (of glucose)
Blood samples analyzed for plasma insulin

Independent Variables

Diet or exercise group
Exercise monitored with pedometer

Control Variables

Description of Actual Data Sample:

Initial N: 24 obese NIDDM patients, 19 males, 5 females

Attrition (Final N): 24; 10 in Diet Alone, 14 in Diet and Exercise group.

Age: mean age Diet Alone: 41.3 +/- 1.8 years, Diet and Exercise: 41.6 +/- 3.5 years

Ethnicity: not mentioned

Other relevant demographics

Anthropometrics: groups were matched with respect to age, sex, and BMI

Location: Japan

Summary of Results:

Demographic data by group:

Group	Age (yr)	BMI		HbA1c (%)
Group	Age (yr)	Before	After	HbA1c (%)
Diet (n=10)	41.3±1.8	31.6±1.8	29.8±2.3	7.0±0.5
Diet + Exercise (n=14)	41.6±3.5	31.2±1.2	27.9±2.0*	7.2±0.6

*significantly greater change than diet group (P<0.01)

Other Findings:

Mean number of steps per day by group during hospitalization:

Diet: 2,500+290 (2 miles)
Diet + Exercise: 19,200+2,100 (~8.4 miles)

Glucose infusion rate (GIR) and metabolic clearance rate (MCR) increased significantly in the diet + exercise group after training. (P<0.001):

GIR increased from 17.21+1.11 to 26.09+1.11 µmol • kg^-1min^-1
MCR increased from 3.0+0.3 to 5.3+0.4 mol • kg^-1min^-1 (P<0.001).

Analysis of variance showed a significant interaction between exercise and time (P=0.0005) for improvement of MCR.

There were significant correlations between the change in MCR and average steps per day (r = 0.7257, P<0.005) in the diet + exercise group.

Author Conclusion:

Walking, which can be safely performed and easily incorporated into daily life, can be recommended as an adjunct therapy to diet treatment in obese NIDDM patients, not only to promote weight loss but also to improve insulin sensitivity.

Funding Source:

University/Hospital:

Aichi Medical University, Nagoya University (both Japan

Reviewer Comments:

This study shows that weight loss alone will not improve insulin sensitivity in obese individuals with type 2 diabetes mellitus. The addition of exercise, however together with weight loss, improves insulin sensitivity.

This study was done during hospitalization. It would be important to repeat this study in free-living individuals to evaluate adherence to the study protocol.

Small sample size - recruitment methods not specified. Groups not equally sized.

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?		???
	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?	???
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)	No
	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?	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
	5.1.	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?	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?	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)?	N/A
	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