DM: MNT (2007)

Citation:

Miller CK, Edwards L, Kissling G, Sanville L. Nutrition education improves metabolic outcomes among older adults with diabetes mellitus:results from a randomized controlled trial. Prev Med 2002;34(2):252-9.

PubMed ID: 11817922
 
Study Design:
Randomized controlled trial
Class:
A - Click here for explanation of classification scheme.
Quality Rating:
Positive POSITIVE: See Quality Criteria Checklist below.
Research Purpose:
To evaluate the impact of a nutrition intervention on the blood glucose and lipoprotein levels of adults 65 years or older with type 2 diabetes for one year or more, and without functional limitations.
Inclusion Criteria:
  • adults with type 2 diabetes mellitus (DM) for at least one year
  • 65 years of age or older

 

Exclusion Criteria:
  • functional limitations
  • impaired cognitive functioning 
Description of Study Protocol:

Recruitment -through advertisements in newspapers, physician's offices, a diabetes support group newsletter, and a newsletter for adults over 55. Letters with invitations to join the study were also sent to those who met study criteria: alumni from the university and patients from an endocrinology practice, a family practice, and an outpatient nutrition center

Design - Randomized Controlled Trial.  Subjects were randomized (based on a computer generated randomization list) to experimental or control group. A pretest-posttest control group design was used to evaluate the intervention.

Blinding used (if applicable) not applicable

Intervention (if applicable) 10 weekly sessions of RD nutrition intervention incorporating principles from information processing, learning theory, and Social Cognitive Theory to meet the needs of older adults. 

Biochemical indices were collected and analyzed at a single outpatient clinical lab. Blood was obtained from each participant at pretest and posttest after a 12-hour fast.

Each person was interviewed, including a brief medical and diet history. This info was used to assist program staff in tailoring intervention to individual needs. The experimental group then received the intervention, 10 1.5-2 hour weekly sessions led by the same RD. All major structural components of the intervention are listed, including written materials, offering only a few new concepts at each lesson, reading food labels, a visit to a grocery store, and goal-setting.

Statistical Analysis - Analysis of the discrete variables was performed using the X2 statistic. Analysis of covariance compared outcomes between groups. The paired t test compared results within groups. Descriptive statistics were examined to verify that assumptions required by each method of analysis were satisfied.

 

Data Collection Summary:

Timing of Measurements - at pretest and posttest (after 10 weeks)

 Dependent Variables

  • glycated hemoglobin (HbA1c) 
  • fasting plasma glucose
  • total cholesterol
  • LDL cholesterol
  • HDL cholesterol
  • Triglycerides

Independent Variables

  • Control group or nutrition intervention of 10 weekly education/informational sessions

Control Variables not specified

 

Description of Actual Data Sample:

Initial N: 98 (53% women)

Attrition (final N): 92 completed the study. No differences in demographic characteristics

Age: control (mean 73.0 ± 4.2), and experimental (mean 72.1 ± 4.2)

Ethnicity: control (81% Caucasian, 19% African American), Experimental (84% Caucasian, 16% African American)

Other relevant demographics: no significant differences in education or household income

Anthropometrics -  duration of diabetes: control 8.2 ± 7.9, experimental 6.2 ± 7.9; BMI control 30.0 ± 5.3, experimental 29.0 ± 5.3.

Location: North Carolina

 

Summary of Results:

 

Metabolic Outcome

Goal

Pretest percentage

Control

Pretest percentage Experimental

Posttest percentage Control Posttest percentage Experimental

Total cholesterol

< 200 mg/dl

23.9

28.3

26.1 35.9
LDL-cholesterol < 100mg/dl 11.2 15.7 14.1 20.7

HDL cholesterol

 >45 mg/dl

 25.0

 20.7

26.1 18.5
Triglycerides < 200 mg/dl 35.9 37.0 38.0 42.4
Fasting plasma glucose 90 - 130 mg/dl 20.9 16.5 16.3 23.9
HbA1c < 7.0% 27.2 26.1 23.9 33.7

Other Findings

 

Author Conclusion:
This study has shown evidence that education, including about the food label, is beneficial among older adults with type 2 diabetes mellitus. Nutrition education can improve metabolic outcomes, especially glycemic control, among older adults. The education must be of sufficient duration and quality  to facilitate self-management practices.
Funding Source:
Reviewer Comments:
The intervention by the RD was described extensively. Small sample size. Good discussion of implication and limitations.
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? 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? ???
  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? 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)? N/A
  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? 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