EAL

Diabetes and Physical Activity

Citation:

Study Design:

Class:

- Click here for explanation of classification scheme.

Quality Rating:

Research Purpose:

To determine the effect of postprandial high intensity exercise on glucose homeostasis in males diagnosed with type II diabetes mellitus.

Inclusion Criteria:

Sedentary type II diabetic men treated with diet only. Met WHO criteria for type 2 diabetes.
Normal cardiovascular, renal, hepatic, gastrointestional and neurological functions as assessed by clinical exams, ECG, blood pressure and standard lab results.

Exclusion Criteria:

Females, since gender could affect the relationship between metabolic response and exercise intensity.

Description of Study Protocol:

Recruitment: No details provided.

Design: Randomized Clinical Trial.

Blinding Used (if applicable): Lab tests.

Intervention (if applicable): Subjects were randomized to 1 of 2 protocols separated by 14 days, done on the day of rest or on the day of exercise and after breakfast. On the exercise day, participants had 4 ergometer cycle rides, separated by 6 minute resting periods. The exercise sessions were 3 minutes long at a previously determined load to reach a required 50% of VO2 max. This was followed by a 4 minute load previously determined to reach a required 100% of VO2 max.

Statistical Analysis: Two-way repeated measures analysis of variance was used to determine differences over time. Significant F ratios required the student-Newman-Keuls test to find the statistical significance. To determine differences between single data on resting days versus exercise days, the paired Student's t test was used. For unpaired data, the Student's t test was used if data differed between this study and the author's previous study on different subjects.

Data Collection Summary:

Timing of measurements: VO2 max was obtained 7-11 days pre-study in order to determine workload estimates for each participant. Subsequently, participants rested during the first data collection and 14 days later exercised during the data collection. In both cases, fasting subjects arrived early in the day. One cannula was used to infuse radioactive glucose, and a second cannula was used to draw blood. After radioactive tracer equilibrium was obtained, a 20 min breakfast was served (macronutrient portions adjusted to each participant's weight). Lunch was served 4 hours later. During equilibrium and until 4 hours post-lunch, blood was sampled. Urine was sampled upon arrival, before breakfast, before lunch, 4 hours after lunch, all stored immediately at -20 degrees C. Expiratory gas collected for five minutes at 15 min intervals before breakfast, and at 35 min, 65 min (resting day only), 85 min (resting day only), and 230 min post breakfast, and at 35, 65, 85, and 230 min after lunch. Prior to meals, muscle biopsies were taken.

Dependent variables:

Blood samples analyzed for glucose, insulin, C peptide, lactate, glycerol
Urine samples
Muscle glycogen measured through muscle biopsy from the quadriceps, via Bergstrom needle through a 10-mm long incision

Independent variables:

On the exercise day, participants had 4 ergometer cycle rides, separated by 6 minute resting periods. The exercise sessions were 3 minutes long at a previously determined load to reach required 50% of VO2max. This was followed by a 4 minute load previously determined to reach a required 100% of VO2max.

Control variables:

Description of Actual Data Sample:

Initial N: 8 males total

Attrition (final N): 8, no attrition

Age: 56 +/- 2 years

Ethnicity: None provided

Other relevant demographics: Met World Health Organization Classification of Diabetes Mellitus. Fasting plasma glucose concentrations: 9.2 +/- 0.5 mmol/l. A1C: 6.0 +/- 0.3%. VO2max: 29 +/- 2 ml/min/kg.

Anthropometrics: Weight 93.5 +/- 4.9 kg. BMI: 29.2 +/- 1.2 kg/m².

Location: Denmark

Summary of Results:

Other Findings:

Fasting plasma concentrations of glucose, insulin and C peptide were identical on the 2 experimental days.

Breakfast areas under the curve for glucose, insulin, and C-peptide were lower on the exercise day compared to the rest of the day (P < 0.05) over 240 minutes.

Area under curve (AUC) for various components (exercise vs. no exercise):

Glucose: 538 +/- 94 vs. 733 +/- 64 mmol/L

Insulin: 16 +/- 4 vs. 22 +/- 3 pmol/ml

C peptide: 143 +/- 22 vs. 203 +/- 29 pmol/ml

After breakfast, glucose appearance was unaffected by exercise, whereas disappearance and clearance increased (P < 0.05). After lunch, no differences were observed between experiments.

Glucose increased in clearance after exercise (p<0.05). Muscle glycogen diminished after exercise (p<0.05). Exercise resulted in similar reduction in glucose, insulin, C peptide (p<0.05).

Author Conclusion:

Postprandial high intensity exercise reduces the concentration of glucose and insulin secretion but does not deteriorate glucose homeostasis. Energy expenditure is important rather than peak exercise intensity. Exercising after a meal does not affect glucose homeostasis during a subsequent main meal.

Funding Source:

Government:

Danish Diabetes Association, Danish Diabetes Association

Reviewer Comments:

Lack of information on recruitment. Interventions described, outcomes defined, measures valid, reasonable outcome data.

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?		N/A
	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?	N/A
	3.3.	Were concurrent controls or comparisons used? (Concurrent preferred over historical control or comparison groups.)	N/A
	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?	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.)	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?	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