Meta-analysis of individual patient data in randomised trials of self-monitoring of blood glucose in people with non-insulin treated type 2 diabetes

This study assessed the effectiveness of self-monitoring blood glucose levels in people with non-insulin treated type 2 diabetes compared with clinical management without self-monitoring, and to explore the effects in specific patient groups. The meta-analysis was based on individual participant data.

The data sources were Medline, Embase, and a recent systematic review of trials on self-monitoring of blood glucose. Chief investigators of trials published since 2000 were approached for additional information and individual patient data.

Randomised controlled trials in patients with non-insulin treated type 2 diabetes comparing an intervention using self-monitoring of blood glucose with clinical management not using self-monitoring were included.

A total of 2 552 patients were randomised in the six included trials. A mean reduction in HbA1c level of -2.7 mmol/mol (95% confidence interval (CI) -3.9 to -1.6; 0.25%) was observed for those using self-monitoring of blood glucose levels compared with no self-monitoring at 6 months. The mean reduction in HbA1c level between groups was 2.0 mmol/mol (3.2 - 0.8; 0.25%) at three months (5 trials) and 2.5 mmol/mol (4.1 - 0.9; 0.35%) at 12 months (3 trials). These estimates were unchanged after imputing missing data, and estimates of effect in trials with higher loss to follow-up or a possibility of co-intervention compared with those with lower loss to follow-up and no co-intervention did not differ significantly (p=0.21). The difference in HbA1c levels between groups was consistent across age, baseline HbA1c level, sex, and duration of diabetes, although the numbers of older and younger people and those with HbA1c levels >86 mmol/mol (10%) were insufficient for interpretation. No changes occurred in systolic blood pressure (-0.2 mmHg, 95% CI -1.4 - 1.0), diastolic blood pressure (-0.1 mmHg, -0.9 - 0.6), or total cholesterol level (-0.1 mol/l, 95% CI -0.2 - 0.1).

Evidence from this meta-analysis of individual patient data was not convincing for a clinically meaningful effect of clinical management of non-insulin treated type 2 diabetes by self-monitoring of blood glucose levels compared with management without self-monitoring, although the difference in HbA1c level between groups was statistically significant. The difference in levels was consistent across subgroups defined by personal and clinical characteristics.

Farmer AJ, et al. BMJ 2012:344 [doi: 10.1136/bmj.e486] (published 27 February 2012).