EAL

DM: Blood Glucose Self-Monitoring (2007)

Citation:

Study Design:

Class:

- Click here for explanation of classification scheme.

Quality Rating:

Research Purpose:

The purpose of this study was to evaluate the effectiveness of self-monitoring blood glucose levels to improve glycemic control.

Inclusion Criteria:

Member of Kaiser Permanente Medical Care Program of Northern California (n= ~3million)
Identified on Kaiser Permanente Diabetes Registry
Adults age 19 years or older
Kaiser Permanente membership continuous between 1/1/96-12/31/97
Received full pharmacy benefits
Had an A1C measured in 1997

Exclusion Criteria:

Members who had not responded to the self-administered questionaire or computer assisted telephone interview, or did not provide enough information to allow for statistical analysis.

Description of Study Protocol:

Recruitment

All subjects were recruited from Northern California Kaiser Permanente.

Design: This was a cohort study with retrospective analysis of data

Blinding Used (if applicable): Not applicable

Intervention (if applicable): Not applicable

Statistical Analysis: Comparisons of study data was done with chi-squared test for categorical variables, the two-sample t test for normally distibuted continuous variables, and the Wilcoxon rank sum test for continuous variables with skewed distributions. General linear models (SAS Proc GLM) were used to assess the relations between A1C level and adherence and between A1C level and ordinal self-monitoring level. Regression models were adjusted for age, sex, race, education, occupation, income, duration of diabetes, medication refill adherence, clinic appointment "no show" rate, annual eye exam attendance, use of lifestyle changes (exercise and food choices), smoking, alcohol use, hospitalization and ER visits and the number of daily insulin injections.

Data Collection Summary:

Timing of Measurements

Based on collected data, subjects could be categorized according to type of diabetes, monitoring strip usage, and adherent or nonadherent according to American Diabetes Association Clinical Practice Recommendations from 1997, 1998, 1999. These recommendations suggest monitoring three times per day for type 1 diabetes, daily for type 2 diabetes treated pharmacologically, and no recommendations given for diet-controlled type 2 diabetes.

Dependent Variables

Number of glucometer strips redeemed at Kaiser pharmacies during 1996 (baseline period) was determined.
A1C levels found from 1997 (followup period)

Independent Variables

Information collected from self-administered questionaire or computer assisted telephone interview.

Control Variables

Automated pharmacy records were used to determine a medication refill adherence index.
Number of hospital stays, emergency room visits, outpatient appointments missed, and number of ophthalmology exams during baseline period were determined from administrative utilization files.
Neighborhood socio-economic levels were characterized using the member's home address and data from 1990 census.

Description of Actual Data Sample:

Initial N: 48,614 subjects

Attrition (Final N): 24,312 adult patients with diabetes responded to the questionnaire and telephone survey who also had data available on daily glucometer strip utilization and HbA1C in early 1997. 24,302 were excluded, these subjects were stratified by therapy alone and analysed as a comparison group. About 50% men, 50% women.

Age: 19 years and older

Ethnicity: Mostly non-Hispanic White

Other relevant demographics:

Anthropometrics:

Location: California

Summary of Results:

**Study Results**
Strip usage	Type 1 diabetes adherent/nonadherent n= 395/764	Type 2, on insulin adherent/nonadherent n=3011/2541	Type 2, oral agents only adherent/nonadherent n=2543/10,243	Type 2, diet controlled adherent/nonadherent n=1987/2828
None	0/190 (p 0.001)	0/1050 (p 0.001)	0/6192 (p 0.001)	0/2828 (p 0.001)
Less than daily	0/189 (p 0.001)	0/1491 (p 0.001)	0/4051 (p 0.001)	1370/0 (p 0.001)
At least once per day	0/385 (p 0.001)	3011/0 (p 0.001)	2543/0 (p 0.001)	617/0 (p 0.001)
At least 3 times per day	395/0 (p 0.001)	NA/NA	NA/NA	NA/NA
A1C	7.6±1.4/8.8±1.9 (p 0.0001)	8.2±1.7/8.9±2.2 (p 0.0001)	8.0±1.8/8.7±2.3 (p 0.001)	7.6±1.8/8.1±2.3 (p 0.001)

Other Findings

Adherent subjects were more likely to be white, female and have greater education and income.

Healthy lifestyle behaviors were more common in the adherent subjects, however, more hospitalizations and emergency room visits were seen in the adherent type 2 subjects.

Consistent findings were found in the comparison group.

Author Conclusion:

More frequent self-monitoring of blood glucose levels was associated with clinically and statistically better glycemic control regardless of diabetes type or therapy.

These findings support the 1997 recommendations for self-monitoring of blood glucose of the American Diabetes Association.

Funding Source:

Government:

NIH

Industry:

Kaiser Institute

Other:

University/Hospital:

ADA

Reviewer Comments:

This study had a large enough sample size to show a statistically significant difference between those who regularly checked blood glucose compared to those who did not. This study is relatively short term. A 1% unit improvement in A1C is significant.

An important finding was that subjects who participated in regular self-monitoring of blood glucose also were more adherent to lifestyle changes. This is a key article that supports home blood glucose testing.

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?	???
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)	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?	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.)	Yes
	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?	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?	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.)	N/A
	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?		Yes
	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?	No
	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?	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)?	Yes
	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?		???
	10.1.	Were sources of funding and investigators' affiliations described?	???
	10.2.	Was the study free from apparent conflict of interest?	???