January 10, 2014

Poor SMBG Studies Lead to Wrong Conclusions

When participants that know something about self-monitoring of blood glucose (SMBG) are excluded from studies, when participants are given only testing supplies and not education, and when the study is too short, it is not surprising that a meta-analysis of SMBG studies arrives at an incorrect conclusion.

What is even more shameful is that the Centers for Medicare and Medicaid Services (CMS) also believes the incorrect conclusions and is penalizing the elderly by forcing many to rely on unreliable blood glucose meters and test strips. This is on top of the limited number of test strips they will be reimbursed for in a period for testing. What this does is force many Medicare members to pay for their own testing supplies, especially among those that know the value of blood glucose testing and do not want to manage their diabetes in the blind.

The value of self-monitoring of blood glucose is established in patients with type 1 and type 2 diabetes taking insulin. Yet, discrimination is the password for type 2 people with diabetes on oral medications. A working hypothesis has been developed that self-monitoring in these patients could prompt them to adjust their diet and lifestyle based on the immediate feedback and this would improve glycemic control.

A meta-analysis published in the Cochrane Library this year has concluded that this hypothesis is false. The meta-analysis included 12 randomized controlled trials with 3259 patients with type 2 diabetes and not on insulin. The 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.

The trials of self-monitoring was shown to provide a small, statistically significant improvement in HbA1c at 6 months and at 12 months, the benefit was not statistically significant and was even smaller. The authors concluded that the overall benefit of self-monitoring in these patients is minimal at 6 months and disappears at 12 months. Patients in this part of the analysis had diabetes for at least 1 year. The study authors claim the results are consistent with those published in 2010 study of 10 trials comparing self-monitoring with no self-monitoring.

The information not explained may be more important than the meta-analysis of 12 studies. How long were the studies that were used in the meta-analysis? This is carefully left out of the analysis data. Also missing was any statements of whether education was given any of the participants. Unknown is the amount of testing supplies furnished the participants or for how long. If the testing supplies were furnished for the first six months and stopped, it is reasonable that the next six months might not show any significant improvement.

This is why they can claim that the working hypothesis is false by not making information available to the reader. I don't believe the meta-analysis was correctly done because of the missing information and this is represented in late 2013 when the original was published in March 2012.

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