Self-monitoring of glucose in type 2 diabetes mellitus: a Bayesian meta-analysis of direct and indirect comparisons

Objective: To evaluate the relative effectiveness of interventions with self-monitoring blood glucose and self-monitoring of urine glucose, versus interventions without self-monitoring, in terms of HbA(1c) reductions in type 2 diabetes mellitus. Methods: Thirteen published full reports on randomised controlled trials investigating the effects of self-monitoring glucose were identified by a systematic search of Medline, Embase, the Cochrane Library (1966-Nov 2005) and previous reviews. Three types of studies were included: self-monitoring of blood glucose versus no self-monitoring, self-monitoring of blood glucose versus self-monitoring of urine glucose and self-monitoring of blood glucose with regular feedback versus monitoring without feedback. The internal validity of studies was assessed systematically by two reviewers, using 13 criteria of a validated list. Results from the three types of studies were analysed simultaneously with a Bayesian meta-analysis of direct and indirect comparisons. Results: Adjusted for baseline HbA(1c) level and internal validity, interventions with self-monitoring of blood glucose showed a reduction in HbA(1c) of 0.40 percentage-points (%) (95% credible interval [CrI] 0.07 to 0.70%) in comparison to interventions without self-monitoring. Regular feedback more than doubled the HbA(1c) reduction. Self-monitoring of urine glucose showed comparable results to interventions without self-monitoring (0.02% decrease in HbA(1c); 95% CrI -0.62 to 0.70%). There is a 88% probability that interventions with self-monitoring blood glucose are more effective than interventions with urine glucose monitoring (relative reduction in HbA(1c) is 0.38%, 95% CrI -0.30 to 1.00%). Conclusion: The randomized clinical trials performed to date provided positive results on the effectiveness of interventions with self-monitoring of blood glucose in type 2 diabetes mellitus. Regular medical feedback of the monitored HbA(1c) levels is important. Furthermore, self-monitoring of blood glucose is likely to be more effective than self-monitoring of urine glucose.