Are current clinical trials in diabetes addressing important issues in diabetes care?

Clinical trials assessing interventions for treating and preventing diabetes mellitus and its complications are needed to inform evidence-based practice. To examine whether current studies adequately address these needs, we conducted a descriptive analysis of diabetes-related trials registered with ClinicalTrials.gov from 2007 to 2010. From a dataset including 96,346 studies registered in ClinicalTrials.gov downloaded on 27 September, 2010, a subset of 2,484 interventional trials was created by selecting trials with disease condition terms relevant to diabetes. Of the diabetes-related trials, 74.8% had a primarily therapeutic purpose while 10% were preventive. Listed interventions included drugs (63.1%) and behavioural (11.7%). Most trials were designed to enrol a parts per thousand currency sign500 (91.1%) or a parts per thousand currency sign100 (58.6%) participants, with mean/median times to completion of 1.8/1.4 years. Small percentages of trials targeted persons aged a parts per thousand currency sign18 years (3.7%) or a parts per thousand yen65 years (0.6%), while 30.8% excluded patients > 65 years and the majority excluded those > 75 years. Funding sources included industry (50.9%), NIH (7.5%) or other, with most being single-centre trials of other sponsorship (37.7%) or industry-funded multicentre studies (27.4%). A small number of trials (1.4%) listed primary outcomes including mortality or clinically significant cardiovascular complications. The distribution of trials by global region and US state does not correlate with prevalence of diabetes. The majority of diabetes-related trials include small numbers of participants, exclude those at the extremes of age, are of short duration, involve drug therapy rather than preventive or non-drug interventions and do not focus upon significant cardiovascular outcomes. Recently registered diabetes trials may not sufficiently address important diabetes care issues or involve affected populations.