EAL

DM: Blood Glucose Self-Monitoring (2007)

Citation:

Study Design:

Class:

- Click here for explanation of classification scheme.

Quality Rating:

Research Purpose:

Study 1: To determine if the continuous glucose monitoring system (CGMS) is a more sensitive approach to detecting symptomatic and/or asymptomatic hypoglycemic events (number and duration) in intensively treated (MDI) children with type 1 diabetes as compared with standard monitoring systems

Study 2:

To determine whether periodic application of CGMS would help to reduce the hypoglycemic risk, without compromising glycometabolic control
To validate the use of CGMS in childhood

Inclusion Criteria:

Children with duration of type 1 diabetes of more than 1 year and absence of ß-cell insulin secretion (C peptide < 0.5 ng/ml)

Exclusion Criteria:

None given.

Description of Study Protocol:

Recruitment

Children who were regular attendees at the authors' Unit of Autoimmune Endocrine Diseases were recruited.

Design

Study 1: Determine correlation of self-monitoring of blood glucose (SMBG) with CGMS over a 72 hr period in 27 children with type 1 diabetes

Study 2: Comparison of glucose control and hypoglycemic events before and after a 6 week period

Blinding used (if applicable): no

Intervention (if applicable)

Study 2:

After baseline CGMS, insulin doses were recalculated and redistributed within the 24-hr period
Subjects were asked NOT to adjust their regular lifestyle (physical activities, dietary habits, social customs during the study)
Seen by a registered dietitian on a regular basis during the study and instructed to follow a nutritional regimen of 55-60% carbohydrate, 25-30% lipids, and 15-20% protein

Statistical Analysis

t-test for unpaired data

Data Collection Summary:

Timing of Measurements

Baseline and 6 weeks later.

Dependent Variables

median glycemia by CSII (MiniMed Inc, Sylmar, CA)
number and duration of hypoglycemic events by CSII as above
insulin requirements by CSII as above
SMBG by Glucotrend 2, Roche Diagnostics, Mannheim, Germany
fructosamine by colorimetric assay (Roche/Hitachi Analyzer)
HbA_1c by spectrophotometric method (Bio-Rad, Richmond, CA)

Independent Variables

Duration of type 1 diabetes

Control Variables

Type of insulin delivery (multiple insulin injections)

Description of Actual Data Sample:

Initial N:

Study 1: 27 children with type 1 diabetes (12 boys, 15 girls)

Study 2: 18 continued the study through 6 weeks (6 boys, 12 girls)

Attrition (final N): none

Age:

Study 1: median age 10.4±0.8 yrs (range, 6-13.1 yrs)

Study 2: (six weeks): median age 11.3 yrs (range, 6.8-13.1 yrs)

Ethnicity: not reported

Other relevant demographics:

at baseline, insulin treatment consisted of 4-5 injections per day
duration of diabetes not provided

Anthropometrics: none provided

Location: Bambino Gesu Children's Hospital, Rome, Italy

Summary of Results:

Study 2 Variables

Baseline, n=18

means±SD

6 weeks, n=18

means±SD

Statistical Significance of Group Difference

fructosamine (µmol/L)

349±24

330±30

P<0.05

HbA_1c (%)

7.6±0.7

7.5±0.5

Other Findings

Study 1:

A high level of concordance was obtained between CGMS glycemic values and those obtained using SMBG (median glycemia of 10.58±1.92 mmol/L and 10.74±1.58 respectively, NS)
CGMS found a significantly higher number of asymptomatic hypoglycemic events vs standard SMBG measurements: 3.6±2.3 vs 0.7±0.9, P<0.0001

Study 2: Insulin therapy adjustments after baseline CGMS had reduced the incidence of hypoglycemia, CGMS vs SMBG (2.5±17 vs 3.9±2.2, P<0.05)

Author Conclusion:

CGMS is not worthwhile in those individuals with irregular daily living habits and food intake.
CGMS is a useful device for detecting asymptomatic hypoglycemia and for readjusting glycemic profiles to reduce hypoglycemic events.

Funding Source:

Reviewer Comments:

While subjects were asked not to change lifestyle (physical activity, dietary habits, social customs), there was no indication that authors measured compliance for these confounding factors.
Only one subject was pubertal, so no comparisons can be made between puberty and prepuberty

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?	???
	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?	???
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?	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?		N/A
	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?	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?	???
	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?	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?	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?	N/A
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?		???
	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?		Yes
	10.1.	Were sources of funding and investigators' affiliations described?	Yes
	10.2.	Was the study free from apparent conflict of interest?	Yes