Achieving HbA1c targets in clinical trials and in the real world: a systematic review and meta-analysis

To review the proportion of diabetic patients reaching recommended therapeutic goals, as reported in intervention trials and observational studies, and to analyse the factors associated with success or failure in achieving these targets.

A systematic review and meta-analysis through a Medline and Embase search for "diabetes" and "HbA1c" has been performed between 1 January 1995 and 1 March 2012 on randomised clinical trials and observational studies on type 1 (T1DM) or type 2 diabetes (T2DM) enrolling at least 200 patient*year.

Out of 169 patient groups in RCTs with results available for analysis, the overall proportion of patients reaching HbA1c ≤ 7 % was 36.6 (34.1-39.1) %. Of these, 8 groups included T1DM subjects [proportion at target (PAT) 27.2 (22.7-32.3) %] and 161 T2DM patients [PAT 37.1 (34.5-39.7) %]. In patients with T2DM on oral agents, at multivariate analysis, higher success rate was associated with higher age and body mass index (BMI), lower duration of diabetes, lower proportion of Caucasians and more recent publication year. Among the insulin treated, only duration of diabetes retained a significant association with success rate. Among 41 groups from cross-sectional studies, 6 and 22 were composed of patients with T1DM and T2DM, respectively, and the remaining 13 included both types. Patients at target for HbA1c were 19.8 (12.4-30.1), 36.1 (31.5-41.0), and 39.0 (32.9-45.3) %, respectively. Higher age, lower BMI, shorter duration of diabetes and a higher proportion of males and Caucasians were associated with a higher success rate.

Available data show that a wide distance remains between recommended targets and actual achievements in routine clinical practice.