A randomised, controlled trial of self-monitoring of blood glucose in patients with type 2 diabetes receiving conventional insulin treatment.

Aims/hypothesis: We evaluated whether self-monitoring of blood glucose (SMBG) leads to better glycaemic control (HbA(1c)) in patients with type 2 diabetes on conventional insulin regimens.

Methods: Patients with type 2 diabetes on a conventional insulin regimen (basal or premixed insulin with or without additional oral glucose-lowering agents) were recruited at study centres led by members of the German Diabetes Association. In a randomised, prospective, open 2 × 2 factorial design, the once-weekly performance of four-point glucose profiles (SMBG +; n = 151 patients) was compared with no SMBG (SMBG -; n = 149), and the measuring and transmitting of HbA1c results to the study centres (HbA(1c) +; n = 158, of these 82 SMBG - and 76 SMBG +) was compared with HbA1c measurement without disclosure of results (HbA(1c) -; n = 142, of these 67 SMBG - and 75 SMBG +). Randomised allocation was carried out by a central office, using sequentially numbered, sealed envelopes. The primary endpoint was the reduction of HbA(1c) compared with baseline after 12 months. Secondary analyses were of therapy intensification in response to higher blood or urinary glucose or HbA(1c). Participants and caregivers were not blinded as to the allocation of interventions, whereas the laboratory determining HbA(1c) remained blinded.

Results: Patient characteristics were balanced across groups. A total of 56 patients dropped out. In completers, HbA(1c) was reduced in the SMBG + group from 7.3% to 7.0%, i.e. by 0.3% (0.1%, 0.5%) vs SMBG - from 7.3% to 7.0% and 0.3% (0.2%, 0.5%), respectively, the difference being 0.0% (-0.2%, 0.2%) (p = 0.93). The disclosure of HbA(1c) results had no significant influence, with a difference of 0.1% (-0.1%, 0.4%) (p = 0.28). Values above are mean (95% CI). The ORs for therapy intensification significantly rose as the following increased: proportions of urine samples testing positive for glucose, HbA1c concentrations, and fasting or postprandial glucose concentrations. No important adverse events were associated with the interventions.

Conclusions/interpretation: SMBG profiles once weekly or the disclosure of HbA(1c) results did not improve glycaemic control in patients with type 2 diabetes on conventional insulin treatment, although indicators of hyperglycaemia increased the likelihood of therapy intensification. Greater intensification may be necessary to impact on glycaemic control.

Trial Registration: www.clinicaltrials.gov (registration code NCT00688363) FUNDING: Deutsche Diabetes-Gesellschaft, Deutsche Diabetes-Stiftung, Bayer Vital GmbH.