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

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.

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 HbA_1c results to the study centres (HbA_1c +; n = 158, of these 82 SMBG − and 76 SMBG +) was compared with HbA_1c 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.

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, HbA_1c concentrations, and fasting or postprandial glucose concentrations. No important adverse events were associated with the interventions.

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.

www.​clinicaltrials.​gov (registration code NCT00688363)

Deutsche Diabetes-Gesellschaft, Deutsche Diabetes-Stiftung, Bayer Vital GmbH