Blood glucose self-monitoring in type 2 diabetes: a randomised controlled trial

Abstract

To determine whether self-monitoring of blood glucose (SMBG), either alone or with additional instruction in incorporating the results into self-care, is more effective than usual care in improving glycaemic control in non-insulin-treated diabetes. An open, parallel group randomised controlled trial. 24 general practices in Oxfordshire and 24 in South Yorkshire, UK. Patients with non-insulin-treated type 2 diabetes, aged > or = 25 years and with glycosylated haemoglobin (HbA1c) > or = 6.2%. A total of 453 patients were individually randomised to one of: (1) standardised usual care with 3-monthly HbA1c (control, n = 152); (2) blood glucose self-testing with patient training focused on clinician interpretation of results in addition to usual care (less intensive self-monitoring, n = 150); (3) SMBG with additional training of patients in interpretation and application of the results to enhance motivation and maintain adherence to a healthy lifestyle (more intensive self-monitoring, n = 151). The primary outcome was HBA1c at 12 months, and an intention-to-treat analysis, including all patients, was undertaken. Blood pressure, lipids, episodes of hypoglycaemia and quality of life, measured with the EuroQol 5 dimensions (EQ-5D), were secondary measures. An economic analysis was also carried out, and questionnaires were used to measure well-being, beliefs about use of SMBG and self-reports of medication taking, dietary and physical activities, and health-care resource use. The differences in 12-month HbA1c between the three groups (adjusted for baseline HbA1c) were not statistically significant (p = 0.12). The difference in unadjusted mean change in HbA1c from baseline to 12 months between the control and less intensive self-monitoring groups was -0.14% [95% confidence interval (CI) -0.35 to 0.07] and between the control and more intensive self-monitoring groups was -0.17% (95% CI -0.37 to 0.03). There was no evidence of a significantly different impact of self-monitoring on glycaemic control when comparing subgroups of patients defined by duration of diabetes, therapy, diabetes-related complications and EQ-5D score. The economic analysis suggested that SMBG resulted in extra health-care costs and was unlikely to be cost-effective if used routinely. There appeared to be an initial negative impact of SMBG on quality of life measured on the EQ-5D, and the potential additional lifetime gains in quality-adjusted life-years, resulting from the lower levels of risk factors achieved at the end of trial follow-up, were outweighed by these initial impacts for both SMBG groups compared with control. Some patients felt that SMBG was helpful, and there was evidence that those using more intensive self-monitoring perceived diabetes as having more serious consequences. Patients using SMBG were often not clear about the relationship between their behaviour and the test results. While the data do not exclude the possibility of a clinically important benefit for specific subgroups of patients in initiating good glycaemic control, SMBG by non-insulin-treated patients, with or without instruction in incorporating findings into self-care, did not lead to a significant improvement in glycaemic control compared with usual care monitored by HbA1c levels. There was no convincing evidence to support a recommendation for routine self-monitoring of all patients and no evidence of improved glycaemic control in predefined subgroups of patients.