Recruitment to a cinical trial improves glycemic control in patients with diabetes

OBJECTIVE - We assessed the effect upon AlC of recruitment to a clinical trial in patients with diabetes who had been screened and interviewed to determine eligibility but whose therapy was otherwise unchanged. RESEARCH DESIGN AND METHODS - Eligible trials were selected from the global program of an insulin manufacturer. Included were studies in which patients were seen on a single screening visit, pharmaceutical therapy was not altered before randomization, and AlC was measured in a central laboratory at both screening and randomization. Three trials involving patients with type I diabetes (n = 429) and three trials involving patients with type 2 diabetes (n = 611) were identified for analysis. The main outcome measure was change in AlC. Separate regression equations on the change in AlC were fitted for type 1 and type 2 diabetes and included effects of baseline AlC and the interval between the screening and randomization visits. RESULTS - AlC changed by -0.13% (range +0.09 to -0.26%) in those with type I diabetes at a median of 28 days and by -0.16% (-0.14 to -0.27%) for those with type 2 diabetes at a median of 14 days. The mean change in AlC in those with an interval of >= 28 days was -0.24% for those with type I diabetes and -0.23% for those with type 2 diabetes. The reduction was proportional to initial AlC, with large decreases in those with the poorest initial control but no overall change in those at or below the 10th percentile of AlC. CONCLUSIONS - Recruitment to a clinical trial, independent of any therapeutic intervention, produces improvements in glucose control.