EAL

DM: Blood Glucose Self-Monitoring (2007)

Citation:

Study Design:

Class:

- Click here for explanation of classification scheme.

Quality Rating:

Research Purpose:

To compare the demographic and clinical characteristics of Veteran Administration (VA) patients with type 2 diabetes receiving oral hypoglycemic medications who perform and do not perform self-monitoring of blood glucose (SMBG)
To determine the relationship between SMBG, the duration of monitoring, and glycemic control
To determine the relationship between SMBG and the number of laboratory tests performed to measure blood glucose and A1C levels

Inclusion Criteria:

Patients receiving care at a Texas VA center between October 1, 1999, and September 30, 2002
Diabetes (type 2) diagnosis
Seen for three years continuously or receiving their care regularly from the VA center (assigned primary provider, at least 2 outpatient clinic visits, and at least one A1C recorded each year for three years)

Exclusion Criteria:

Not on oral meds for diabetes
On insulin
Did not meet criteria of strip usage for the 4 study groups

Description of Study Protocol:

Recruitment

Patients receiving care at a Texas VA center between October 1, 1999, and September 30, 2002

Design

Retrospective cohort study design
Cohort divided into 4 study groups based on strip usage: Group 1 did not receive monitoring strips during the three year study period; Group 2 received strips in fiscal year (FY) 2002 only; Group 3 received strips in FYs 2001 and 2002; Group 4 received strips during all three study years.

Blinding used (if applicable)

Not applicable

Intervention (if applicable)

Not applicable

Statistical Analysis

Nonparametric statistics (Kruskal-Wallis test) was used to compare demographic and clinical characteristics between groups.
Robust regression was used to analyze the relationship between SMBG and glycemic control in FY 2002.
P value of 0.05 was established as significant for all analyses.

Data Collection Summary:

Timing of Measurements

A1C reviewed from tests done in all FYs
Timing of measurements not directed by study

Dependent Variables

Mean A1C in FY 2002

Independent Variables

Baseline A1C in FY 2000
Age
Case-mix score (which accounts for presence of comorbidities)
Body mass index (BMI)
Race
Duration of monitoring (study group)

Control Variables

Not discussed

Description of Actual Data Sample:

Initial N: 1185 patients received oral medications during all three FYs

Attrition (final N): 976 met criteria for inclusion (97.4% male)

Mean Age: 62.7 ± 10.7 years

Ethnicity: Hispanic (48.1%), non-hispanic white (38.4%), non-hispanic black (8%), unknown (5.5%)

Other relevant demographics: In review of case-mix scores, these study subjects scored higher (more comorbidities) than the Medicaid population on which the national weights are based.

Anthropometrics: Mean BMI was 30.8 ± 5.6 kg/m²

Location: Texas, USA

Summary of Results:

**Median (and interquartile range) of A1C results during study period**
	Group 1 (no strips) n= 161	Group 2 (one FY of strips) n= 75	Group 3 (two FY of strips) n= 138	Group 4 (three FY of strips) n= 602
A1C result (%) FY 2000 FY 2001 FY 2002	7.10 (6.40-8.13) 6.87 (6.10-7.80) 6.80 (6.80-7.85)	7.00 (6.35-7.93) 7.25 (6.43-7.85) 7.23 (6.45-8.17)	7.03 (6.20-7.03) 6.68 (5.82-6.68) 6.60 (5.80-6.60)	7.13 (6.40-8.10) 6.70 (6.10-7.54) 6.79 (6.17-7.61)

Other Findings

There was no significant difference between the 4 groups in A1C, BMI, or degree of illness (case-mix score), as measured by the Chronic Illness and Disability Payment system.
The median strip usage (for all groups) was 0.56 strip/day (about 4 times per week).
As determined from statistical analysis of FY 2002, age and being hispanic were predictors of A1C. Duration of monitoring was not a predictor or A1C.

Author Conclusion:

SMBG was not associated with glycemic control in VA patients with type 2 diabetes mellitus managed on oral hypoglycemic medications.
Possible explanation for lack of association between SMBG and A1C is this population did not perform SMBG often enough to show a difference. Additionally, this population overall had good glycemic control.

Funding Source:

Reviewer Comments:

Frequency of strip usage per study group not discussed
Statistical analysis not done within groups (ie group 3) to compare A1C during testing years and non-testing years
The number of subjects in each group differed

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)	N/A
	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?	No
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?	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?	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?		N/A
	4.1.	Were follow-up methods described and the same for all groups?	N/A
	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%.)	N/A
	4.3.	Were all enrolled subjects/patients (in the original sample) accounted for?	N/A
	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?		???
	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.)	???
	5.3.	In cohort study or cross-sectional study, were measurements of outcomes and risk factors blinded?	???
	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?		???
	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?	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?	No
	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?	N/A
	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?	No
	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?		???
	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?	No
	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