Is the Frequency of Self-Monitoring of Blood Glucose Related to Long-Term Metabolic Control? Multicenter Analysis Including 24 500 Patients from 191 Centers in Germany and Austria

Introduction

The increasing prevalence of diabetes mellitus and its long-term complications are associated with an expanding health care problem ([O'Brien et al., 2003]). This situation results in a more and more critical discussion regarding the cost effectiveness of clinically established tools that are used in diabetes care. A major concern in this debate that is primarily focused on the treatment of patients with type 2 diabetes is represented by the practice and frequency of self-monitoring of blood glucose (SMBG).

In the daily management of type 1 diabetes, SMBG is the recommended glycemic monitor that enables improved glycemic control. Maintaining blood glucose at or very near the normal range is known to decrease progression of microvascular disease in patients with type 1 diabetes ([The Diabetes Control and Complications Trial Research Group, 1993]), and the cost effectiveness of this policy has been reported using data from the diabetes control and complications trial ([Herman and Eastman, 1998]).

Evidence for the efficacy of SMBG in type 2 diabetic patients is, however, still conflicting ([Coster et al., 2000]; [Franciosi et al., 2005]), although some studies suggest improvement of metabolic control in type 2 diabetes using SMBG. The United Kingdom Prospective Diabetes Study showed that improved BG control decreases the frequency of new-onset microvascular complications and delays the progression of established microvascular complications in patients with type 2 diabetes ([UKPDS 33, 1998]). A subsequent cost effectiveness analysis revealed that the increased therapy costs of intensive blood glucose control are largely offset by significantly reduced costs of complications ([Gray et al., 2000]). Karter et al. demonstrated in a large observational study that frequent BG monitoring significantly improved HbA1c-levels in type 2 diabetic patients treated with insulin, oral antidiabetics, or diet only ([Karter et al., 2001]). Furthermore, a cohort study from the Veterans Administration showed improved glycemic control with lowered HbA1c in patients with insulin-treated type 2 diabetes who performed SMBG ([Murata et al., 2003]). A positive correlation between SMBG and the reduction of HbA1c-levels has also been described in two recent studies on non-insulin-treated patients ([Guerci et al., 2003]; [Schwedes et al., 2002]). Finally, in the latest guidelines on the management of type 2 diabetes, SMBG was recommended by the American Diabetes Association for glycemic monitoring ([American Diabetes Association, 2004]).

However, according to the cost-intensive factor of SMBG for the health care system, the optional daily glucometer strip utilization in diabetes care is still under debate ([Davidson, 2005]; [Ipp et al., 2005]). Here, we analyzed in an observational study whether the frequency of SMBG is related to long-term metabolic control by using anonymized data of 24 500 patients that were regularly transferred from 191 centers to a central computer-based database for quality management and documentation of diabetes in Germany (DPV-Wiss-database).

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