Self-monitoring of blood glucose in tablet-treated type 2 diabetic patients (ZODIAC)

Whether self-monitoring of blood glucose (SMBG) improves glycaemic control in patients with type 2 diabetes mellitus (T2DM) not using insulin is questionable. Our aim was to investigate the effects of SMBG in patients with T2DM who were in persistent moderate glycaemic control whilst not using insulin.

Patients were eligible when between 18 and 70 years of age, with an HbA1c between 7 and 8.5%, using one or two oral blood glucose lowering agents. Forty-one of the anticipated 52 patients were randomly assigned to receive either SMBG added to usual care, or to continue with usual care for one year. A fasting glucose value and three postprandial glucose values were measured twice weekly (including a Saturday or a Sunday). The primary efficacy parameter was HbA1c. Furthermore, health-related quality of life and treatment satisfaction were assessed using the Short-form 36 Health Survey Questionnaire (SF-36), the Type 2 Diabetes Symptom Checklist (DSC-r), the Diabetes Treatment Satisfaction Questionnaire (DTSQ) and the WHO -Wellbeing Index (WHO-5).

Change in HbA1c between groups was -0.05% (95% CI: -0.51, 0.41; p=0.507). Also, there were no significant changes between groups on the DTSQ , DSC type 2, WHO-5 or SF -36, except for the SF -36 dimension 'health change' which was lower in the SBMG group (mean difference: -12 (95% CI: -20.9, -3.1).

On top of the absence of a clinical benefit, tablet-treated T2DM patients experienced some worsening of their health perception. We therefore argue that the use of SMBG in this patient group is questionable, and its unlimited use and promotion should be reconsidered.