Evidence-based Synthesis Program 

Self-Monitoring of Blood Glucose in 

Patients with Type 2 Diabetes 

Mellitus: Meta Analysis of 

Effectiveness

Department of Veterans Affairs

Health Services Research & Development Service

September 2007

Investigators:

Paul Shekelle, MD, PhD 

Director

 

Brett Munjas, BA

Project Manager/Literature Database Manager

Maria Romanova, MD

Ali Towfigh, MD

Physician Reviewers

Jane Weinreb, MD

Content Expert

Annie Zhou, MS

Marika Suttorp, MS

Statisticians

Prepared for: 

Department of Veterans Affairs

Veterans Health Administration

Health Services Research & Development Service

Washington, DC 20420 

Prepared by:

Greater Los Angeles Veterans Affairs Healthcare 

System/Southern California/RAND Evidence-based 

Practice Center 

Los Angeles, CA
HSR&D Evidence Synthesis Program – iii 

Home Glucose Monitoring 

EXECUTIVE SUMMARY 

BACKGROUND 

Diabetes is a prevalent and costly disease in Veterans. Control of blood glucose is an important VA 

objective. Self-monitoring of blood glucose (SMBG) is advocated as a method to better achieve 

control. 

The Key Questions were: 

Key Question 1. Is regular SMBG effective in achieving target A1c levels for patients with 

type 2 diabetes? 

Key Question 2. Is regular SMBG effective in maintaining target A1c levels for patients with 

type 2 diabetes? 

Key Question 3. Does regular SMBG reduce the frequency of hypoglycemia in patients with 

type 2 diabetes? 

Key Question 4. Is there evidence that different frequencies of testing result in differences in 

improvements in A1c? 

METHODS 

We searched PubMed from 2004-2006 using standard search terms. We performed an update search 

in July 2007. Titles, abstracts, and articles were reviewed in duplicate by physicians trained in the 

critical analysis of literature. Data were extracted by quantitative analysts. Pooled analyses were 

performed for trials with A1c outcomes at six months and 12 months or greater of follow-up. All 

other data were narratively summarized. 

RESULTS 

We screened 52 titles, 14 were rejected, and we performed a more detailed review on 38 articles. 

From this, we identified 14 randomized controlled trials (RCTs) that measured the effect of SMBG 

compared to a group not receiving SMBG and monitored A1c levels with at least three months of 

follow-up. Four trials were excluded; one because it presented duplicate data and three because they 

evaluated SMBG in both the control and intervention groups, leaving 10 trials contributing to the 

efficacy analysis. We identified five observational studies assessing effectiveness in diabetic 

Veterans. 

KEY QUESTION #1: Is regular SMBG effective in achieving target A1c levels for patients 

with type 2 diabetes? 

STUDIES OF EFFICACY 

Achieving Target A1c Levels 

There is little evidence to draw a conclusion about the effect of SMBG at achieving target A1c 

levels. We judged the strength of this evidence as very low. [GRADE: Very Low = Any estimate of 

effect is very uncertain.] 
HSR&D Evidence Synthesis Program – iv 

Home Glucose Monitoring 

Improving Glycemic Control 

We found that adding SMBG along with education, counseling, (and some times other components) 

results in a statistically significant decrease in A1c level of an absolute 0.21% at six months. Results 

at three months and one year are more variable, although there is a suggestion that this benefit may 

continue out to at least one year. 

We judged the strength of evidence for this outcome as moderate, because individual trials did not in 

general report significant results and interventions were heterogeneous. [GRADE: Moderate= 

Further research is likely to have an important impact on our confidence in the estimate of effect and 

may change the estimate.] 

STUDIES OF EFFECTIVENESS IN VETERANS 

Five observational studies of SMBG effectiveness in Veteran populations did not report statistically 

significant improvements in glycemic control. [GRADE: Very Low = Any estimate of effect is very 

uncertain.] 

KEY QUESTION #2: Is regular SMBG effective in maintaining target A1c levels for patients 

with type 2 diabetes? 

We did not identify any trials that directly assessed this question. Therefore, we draw no conclusion 

and the strength of evidence is very low. [GRADE: Very Low = Any estimate of effect is very 

uncertain.] 

KEY QUESTION #3: Does regular SMBG reduce the frequency of hypoglycemia in patients 

with type 2 diabetes? 

The limited evidence available indicates that SMBG increases the frequency of recognized 

hypoglycemia. This is due to an increase in asymptomatic low blood sugar readings, and also an 

increase in mild-to-moderate symptomatic episodes. There is scant evidence about the effect of 

SMBG on more clinically significant hypoglycemia. We judge the strength of evidence for SMBG 

increasing asymptomatic and mildly symptomatic hypoglycemia as moderate. [Moderate = Further 

research is likely to have an important impact on our confidence in the estimate of effect and may 

change the estimate.] 

KEY QUESTION #4: Is there evidence that different frequencies of testing result in 

differences in improvements in A1c? 

We used meta-regression to assess the effect of the reported frequency of SMBG use in the RCTs 

(measures as times/week) on differences in A1c level compared to control. No association was found 

(p=0.99). Therefore we draw no conclusion about the effect of frequency of SMBG monitoring on 

A1c values, and judge the strength of the evidence to be very low. [GRADE: Very Low = Any 

estimate of effect is very uncertain.]