EAL

DM: Blood Glucose Self-Monitoring (2007)

Citation:

Study Design:

Class:

- Click here for explanation of classification scheme.

Quality Rating:

Research Purpose:

To determine if the continuous glucose monitoring system (MiniMed Sylmar)

is more useful than frequent capillary glucose measurements when modifying treatment and improving glucose control of patients with type 1 diabetes
is useful for investigating the incidence of unrecognized hypoglycemias in type 1 and type 2 diabetic patients
has technical problems related to use

Inclusion Criteria:

Type 1 patients: inadequate control

Type 2 patients: none given

Exclusion Criteria:

None given

Description of Study Protocol:

Recruitment

Not provided

Design: Randomized Controlled Clinical Trial

Comparison of HbA_1c in 40 individuals with type 1 diabetes who were monitored for three days with CGMS after which glycemic treatment was modified and followed for three months vs 35 individuals whose treatment was modified based on multiple daily measurements and followed for the same period of time.
Frequency of asymptomatic hypoglycemias detected by the CGMS (glucose values < 60 mg/dl) in all subjects monitored on the CGMS for 3 days (40 type 1, 30 type 2)

Blinding used (if applicable): no

Intervention (if applicable)

Glycemic treatment of study group (type 1) subjects modified based on results of three days of monitoring with CGMS. In 31 type 1 study subjects, the type and doses of insulin were adapted to the glucose profile obtained; in 9, treatment with CSII was started and basil rate and boluses were adapted to the CGMS register.
Glycemic treatment of control group modified based on multiple capillary glucose measurements (at least eight measurements per day for three days). In 25 control subjects, the type and doses of insulin were modified; in 10, treatment with CSII was started and basal and boluses were individually adapted to the glucose profile
All patients were evaluated by a clinician between 2 and 4 times over the 3 month period. Diet, treatment of hypoglycemia, and exercise were revised individually by a nurse during 3 to 4 sessions during the 3 month period

Statistical Analysis

Paired t test used to compare HbA_1cbefore and after the study and to compare age and diabetes duration between groups
Fisher's test to compare sex distribution in the groups

Data Collection Summary:

Timing of Measurements

Baseline (before the 3 day monitoring period) and 3 months later for the type 1 study
3 days of CGMS monitoring for the asymptomatic hypoglycemia information

Dependent Variables

HbA_1c by DCA 2000 system, Bayer, NY

Independent Variables

Type 1 and type 2 diabetes

Control Variables

none

Description of Actual Data Sample:

Initial N:

study group: 40 individuals (18 male, 22 female) with type 1 diabetes
control group: 35 individuals (17 male, 18 female) with type 1 diabetes
type 2 subjects: 30 individuals (17 male, 13 female

Attrition (final N): none reported

Age: study group, mean of 36.5 ±yrs; control group mean, of 41±10 yrs; type 2 group, mean of 58±11 yrs

Ethnicity: not reported

Other relevant demographics: study group duration of diabetes mean of 17±12 yrs; control group, 21±10 yrs; type 2 group, 12±8 yrs.

Anthropometrics: none provided

Location: Institute of Diabetology, Barcelona, Spain; Diabetes Center, La Coruna, Spain

Summary of Results:

Table: HbA_1c results (CSII = continuous subcutaneous insulin infusion; MII = multiple insulin injections

	Baseline HbA_{1c Mean±SD}	3 month HbA_1c _Mean±SD	Significance, baseline to 3 months
All subjects
Study group n=40	8.3±1.6	7.5±1.2	p<0.01
Control group n=35	8.4±1.4	7.5±0.8	p<0.01
Subjects on CSII
Study group n=9	9.4±2.0	7.2±1.4	p<0.01
Control group n=10	8.1±1.8	7.1±0.6	p<0.01
Subjects on MII
Study group n=31	8.0±1.4	7.6±1.1	p<0.05
Control group n=25	8.0±1.3	7.6±0.9	p<0.05

Other Findings

The CGMS detected unrecognized hypoglycemias in 62.5% of subjects with type 1 diabetes and and 46.6% of subjects with type 2 diabetes, with 73% of all events occurring at night.

Author Conclusion:

1. The CGMS is useful for detecting unrecognized hypoglycemias in subjects with both type 1 and type 2 diabetes

2. The CGMS is not better than standard capillary glucose measurements for improving metabolic control of subjects with type 1 diabetes, regardless of the therapeutic regimen.

Funding Source:

Reviewer Comments:

The report lacks a description of some of the essential components of research design, such as description of randomization; affirmation of informed consent and institutional approval of study
There is no description of how the clinician/nurse may have recommended further changes insulin doses during the 3 months of the study.
There is no discussion of change in lifestyle (diet/exercise) which could also affect HbA_1c
There is no discussion of source of funding for the study

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?	No
	2.2.	Were criteria applied equally to all study groups?	???
	2.3.	Were health, demographics, and other characteristics of subjects described?	No
	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)	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?	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?	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?		No
	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.)	No
	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?		???
	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?	???
	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?	N/A
	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?		???
	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?	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?		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)?	No
	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?	No
10.	Is bias due to study's funding or sponsorship unlikely?		???
	10.1.	Were sources of funding and investigators' affiliations described?	No
	10.2.	Was the study free from apparent conflict of interest?	Yes