DM: Blood Glucose Self-Monitoring (2007)

Citation:
 
Study Design:
Class:
- Click here for explanation of classification scheme.
Quality Rating:
Research Purpose:
  • To evaluate the extent of plasma/blood glucose excursions after meals;
  • To explore the relations among plasma/blood glucose levels at different times of the day; and 
  • To examine the relations between HbA1c (A1C) and plasma/blood glucose levels at different times of the day in a large sample of persons with non-insulin treated type 2 diabetes.
Inclusion Criteria:

Outpatients at the Diabetes Clinic and Outpatients at Home:

  • Type 2 diabetes
  • Non-insulin treated
  • No changes made in diet, treatment, or lifestyle with the 3 months before the study
  • No concomitant chronic diseases
  • No recent acute illness
  • Willingness to return to the clinic five times in 1 day to measure plasma glucose

 Inpatients:

  • Type 2 diabetes patients admitted to the Division of Endocrinology and Metabolic Diseases because of poor metabolic control, screening or staging of chronic diabetes complications between years of 1987-2000
  • No diabetes within the previous 6 months
  • Admission in the morning after an overnight fast
  • No change in diabetes treatment their first hospital day
  • No insulin treatment before admission or for the first day hospital day
  • No changes in diet, treatment, or lifestyle within 3 months before admission
  • No concomitant chronic diseases or recent acute illnesses
Exclusion Criteria:

Outpatients at the Diabetes Clinic and Outpatients at Home:

  • Diabetes diagnosed within the previous 6 months
Description of Study Protocol:

Recruitment

  • Patients screened from those regularly attending the hospital diabetes clinic of Montecchio Maggiore

 Design:  Cross-Sectional Study

  • Simultaneous measurement of plasma/blood glucose and A1C
  • Patients were asked to eat their usual diet (isocaloric for inpatients) the day/days of the study

Blinding used (if applicable)

  • Not applicable

 Intervention (if applicable)

  •  Not applicable

Statistical Analysis

  • Calculations of means, standard deviation, SEM, and simple correlation coefficients
  • Analysis of variance, X2 tests, and multiple linear regression

 

Data Collection Summary:

Timing of Measurements

  • Outpatients at diabetes clinic:  On one day patients had drawn fasting, ~2 hours post-breakfast, pre-lunch, ~2 hours post-lunch, and pre-dinner plasma/blood glucose.  A1C was drawn with first blood draw of the day.
  • Outpatients at home:  On 5 non-consecutive days subjects were to perform home blood glucose monitoring fasting, ~2 hours post-breakfast, pre-lunch, ~2 hours post-lunch, and pre-dinner, and ~2 hours post-dinner.  A1C was drawn in the middle of the month.
  • Inpatients:  On one day patients had drawn fasting, pre-lunch, ~3 hours post-lunch, pre-dinner, and ~2 hour post-dinner plasma/blood glucose.

Dependent Variables

  • A1C

Independent Variables

  • Plasma/blood glucose; measured either with laboratory method of glucooxidase, or Euroflash Lifescan home glucose meters.
  • A1C; measured with high preformance liquid chromatography (reference range was 3.5-5.5%).

 Control Variables

  •  None
Description of Actual Data Sample:

Initial N: see table

Attrition (final N): n/a

Age: see table

Ethnicity: not mentioned

Other relevant demographics: see table

Anthropometrics: see table

Location: Verona, Italy

 

Study subject characteristics
  Outpatients at diabetes clinic Outpatients at home Inpatients
N (men/women)  371 (211/160)  30  455 (229/226)
Mean age (years)  60.3 ± 9.7  60.3 ± 10.3  58.9 ± 11.5
Duration of diabetes (years)  7.8 ± 5.8  8.3 ± 7.3  8.0 ± 6.8
Body Mass Index (kg/m2)  28.5 ± 4.38  28.6 ± 5.9  32.2 ± 8.23
Diet only treatment (% of subjects)  7.9  20.7  12.2
Metformin only treatment (% of subjects)  6.2  10.3  5.3
Sulfonylurea only treatment (% of subjects) 58.3  27.6  49.7
Metformin and Sulfonylrurea treatment (% of subjects) 27.6  41.4  32.8

 

 

 

 

Summary of Results:

 

Simple correlations between A1C and plasma glucose at different times of day
 

Outpatients at diabetes clinic

Outpatients at home

Inpatients
A1C vs prebreakfast  0.483*  0.580*  0.646*

A1C vs postbreakfast

 0.445*

 0.568

 no data

A1C vs prelunch  0.496*  0.673*  0.630*
A1C vs postlunch  0.477*  0.580*  0.550*
A1C vs predinner  0.491*  0.674*  0.620*
A1C vs postdinner  no data  0.495  0.528*
A1C vs daily mean  0.574*  0.685*  0.694*

 * P<0.001

Other Findings

  • Multiple regression analysis showed premeal, but not postmeal plasma glucose to be independent predictors of A1C in both inpatients and outpatients.

 

Author Conclusion:
  • Majority of these study subjects had higher-than-recommended plasma/blood glucose levels and/or exaggerated glucose excursions after meals.
  • High postmeal glucose excursions were often found when A1C was less than 7%.  For this reason the authors suggest self-monitoring of blood glucose (SMBG) at various times during the day, in addition to A1C measurements.
  • Plasma/blood glucose levels thoughout the day were less interrelated as expected (data not shown in this review).  Consequently, fasting glucose is poor indicator of glucose throughout the day.
  • A1C was more related to premeal plasma/blood glucose than postmeal plasma/blood glucose.
Funding Source:
Reviewer Comments:
Good theoretical rationale for need of SMBG.
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) N/A
 
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? ???
  3.1. Was the method of assigning subjects/patients to groups described and unbiased? (Method of randomization identified if RCT) ???
  3.2. Were distribution of disease status, prognostic factors, and other factors (e.g., demographics) similar across study groups at baseline? No
  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? ???
  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.) ???
  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? No
  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.) No
  5.3. In cohort study or cross-sectional study, were measurements of outcomes and risk factors blinded? No
  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? N/A
  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? N/A
  6.4. Was the amount of exposure and, if relevant, subject/patient compliance measured? N/A
  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? 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? N/A
  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)? 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? Yes
  10.2. Was the study free from apparent conflict of interest? ???