Evaluation of self monitoring of blood glucose in non-insulin-treated diabetic patients by randomized controlled trials: little bang for the buck.

Although self monitoring of blood glucose is accepted to be effective in lowering Hb A1c levels in insulin-treated diabetic patients, any benefit in non-insulin-treated patients remains controversial. Observational studies cannot answer this question because of either patient self selection (individuals with healthier life styles chose to perform more SMBG) or physician self selection (patients in poorer control are asked to perform SMBG). Only randomized controlled trials (RCTs) can provide the answer. Of the 14 published bona fide RCTs, nine show no benefit in lowering Hb A1c levels. In four of the five positive ones, the SMBG group received more intensive education and/or treatment than the control group. In the one in which patients in both groups were followed similarly, over 500 patients were required to produce a statistically significant difference of 0.2% favoring SMBG, the clinical significance of which is debatable. Thus, there is scant evidence that very expensive SMBG in non-insulin-treated patients is effective in lowering Hb A1c levels. This lack of benefit argues for redirecting these resources into areas of diabetes care where strong evidence exists for improving diabetes outcomes.