Response to Welschen et al.
We read the article by Welschen et al. (1) in Diabetes Care with interest. It systematically reviewed the effect of self-monitoring of blood glucose (SMBG) in patients with type 2 diabetes who are not using insulin. This review is important and provides an answer to the extensive debate about this interesting topic.
The same authors published a systematic review on the same topic in April 2005 in the Cochrane Library (2). The same articles were included in both reviews. The authors performed a meta-analysis in the review published in Diabetes Care and concluded that there is a 0.39% decrease in HbA1c (A1C) when allowing SMBG. This effect should be interpreted with caution because of the methodological quality of the trials as addressed in the “Methodological issues” section of the review. Also, in one of the two studies in which a statistically significant decrease of A1C was found, only the SMBG group received education (3). A meta-analysis from Ellis et al. (4) concluded that on average, the influence of education itself on A1C is ∼0.32%.
However, in the Cochrane Library review, the authors write “Because of differences in baseline data of the patients and type of interventions between the studies, it was not possible to perform either a meta-analysis and/or subgroup or sensitivity analyses.” In this review, they conclude “SMBG might be effective in improving glycemic control in patients with type 2 diabetes who are not using insulin.”
Within a few months, the authors reach different conclusions regarding methodology and supposed effects based on the same set of available information. Which is true: a clinically relevant reduction in A1C or a conclusion that SMBG might be effective in improving glycemic control in patients with type 2 diabetes who are not using insulin?
