By Mark Abrahams, MD

Reviewed by Loren Wissner Greene, MD, MA (Bioethics), Clinical Associate Professor of Medicine, NYU School of Medicine, New York, NY

Background

While the value of self-monitoring of blood glucose (SMBG) is well established in patients taking insulin (in both type 1 and type 2 diabetes), debate has continued as to its usefulness in type 2 patients not taking insulin.1

It has been a working hypothesis that self-monitoring in these patients could prompt them to adjust their diet and lifestyle — based on the immediate feedback provided by self-monitoring — and result in improved glycemic control. A meta-analysis published in the Cochrane Library this year has concluded that this hypothesis is false.2

Twelve randomized controlled trials in 3259 patients with type 2 diabetes not using insulin were included in the analysis. Primary outcomes were HbA1c, health-related quality of life, well-being, and patient satisfaction. Secondary outcomes were fasting plasma glucose level, hypoglycemic events, morbidity, adverse effects, and costs.2

1. Clar C, et al; Aberdeen Health Technology Assessment Group. Self-Monitoring of Blood Glucose in Type 2 Diabetes: Systematic Review. Health Technol Assess. 2010;14:1-140.
2. Malanda UL, et al. Self-Monitoring of Blood Glucose in Patients With Type 2 Diabetes Mellitus Who Are Not Using Insulin. Cochrane Database Syst Rev. 2012 Jan 18;CD005060.

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Action Points

    No clinically significant improvements in HbA1c, hypoglycemic events, or quality of life were found for self-monitoring of blood glucose in patients not taking insulin in two different meta-analyses.
    The cost of self-monitoring was at least twice as expensive as no self-monitoring.

While the value of self-monitoring of blood glucose (SMBG) is well established in patients taking insulin (in both type 1 and type 2 diabetes), debate has continued as to its usefulness in type 2 patients not taking insulin.1

It has been a working hypothesis that self-monitoring in these patients could prompt them to adjust their diet and lifestyle — based on the immediate feedback provided by self-monitoring — and result in improved glycemic control. A meta-analysis published in the Cochrane Library this year has concluded that this hypothesis is false.2

Twelve randomized controlled trials in 3259 patients with type 2 diabetes not using insulin were included in the analysis. Primary outcomes were HbA1c, health-related quality of life, well-being, and patient satisfaction. Secondary outcomes were fasting plasma glucose level, hypoglycemic events, morbidity, adverse effects, and costs.2

While self-monitoring was shown to provide a small, statistically significant improvement in HbA1c at 6 months (-0.3), at 12 months, the benefit was not statistically significant and was even smaller (-0.1). The authors concluded that the overall benefit of self-monitoring in these patients is minimal at 6 months and disappears at 12. Patients in this part of the analysis had diabetes for at least 1 year.2

These results are consistent with those from another meta-analysis published in 2010 that studied 10 trials comparing self-monitoring with no self-monitoring. That analysis showed a statistically significant reduction in HbA1c of 0.21, which may be of questionable clinical significance.1

The 2010 meta-analysis also showed no effect on hypoglycemic events for self-monitoring.1 Furthermore, in the current meta-analysis, self-monitoring had no effect on the number of symptomatic hypoglycemic events. Interestingly, because a monitoring device may have allowed patients to self-diagnose asymptomatic hypoglycemic episodes, the overall number of reported hypoglycemic events (both symptomatic and asymptomatic) was increased.2

In the current meta-analysis, a qualitative review of the effect of self-monitoring on well-being and quality of life was performed. This showed no effect on patient satisfaction, general well-being, or general health-related quality of life. The authors do, however, comment that, “More research is needed to explore the psychological impact of SMBG and its impact on diabetes specific to quality of life and well-being, as well as the impact of SMBG on hypoglycaemia and diabetic complications.”2

The cost effectiveness of any therapeutic intervention in the current climate is increasingly important. Two trials included in this analysis reported on cost.

One trial compared self-monitoring of blood glucose to self-monitoring of urine glucose. The authors concluded that, for 1 year of use, blood glucose monitoring was 12 times more expensive than urine monitoring. The purchase of a meter may have accounted for much of this increased cost.3 In another trial, the cost of self-monitoring was found to be approximately twice that of usual care.4

In the current meta-analysis, very few data on secondary outcomes were available for analysis, and the effects of self-monitoring on these outcomes were not statistically significant.2

The evidence suggests that SMBG is of limited effectiveness in improving glycemic control in people with type 2 diabetes not using insulin. It also does not appear to be cost effective.

References:

    Clar C, et al; Aberdeen Health Technology Assessment Group. Self-Monitoring of Blood Glucose in Type 2 Diabetes: Systematic Review. Health Technol Assess. 2010;14:1-140.
    Malanda UL, et al. Self-Monitoring of Blood Glucose in Patients With Type 2 Diabetes Mellitus Who Are Not Using Insulin. Cochrane Database Syst Rev. 2012 Jan 18;CD005060.
    Allen BT, et al. Impact of Glucose Self-Monitoring on Non-Insulin-Treated Patients With Type II Diabetes Mellitus. Randomized Controlled Trial Comparing Blood and Urine Testing. Diabetes Care. 1990;13:1044-1050.
    Farmer A, et al. Impact of Self Monitoring of Blood Glucose in the Management of Patients With Non-Insulin Treated Diabetes: Open Parallel Group Randomised Trial. BMJ. 2007;335:132.

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