There are an estimated 371 million people with diabetes in the world.
By 2030, there will be some 550 million with diabetes based on current trends.
As such, research addressing the whole spectrum of diabetes care and treatment is essential.
To examine whether current studies adequately address these needs, Dr Jennifer Green from Duke University Medical Center, Durham, NC, USA, and colleagues analysed diabetes-related trials registered with ClinicalTrials.gov from 2007.
The researchers found 2,484 interventional trials by selecting those with disease condition terms relevant to diabetes.
Of these, 75 percent had a primarily therapeutic purpose while just 10 percent were preventive.
Listed interventions were mostly drugs (63 percent) while few were behavioural (12 percent).
Most of the studies were also small to medium sized, and were designed to enrol 500 or fewer participants (91 percent) or 100 or fewer (59 percent) participants, with mean/median times to completion of 1.8/1.4 years.
A very small proportion of trials targeted persons aged 18 years and under (4 percent).
This may be appropriate given the number of children currently affected by diabetes; however, the estimated 3 percent annual increase in incidence of type 1 diabetes may warrant greater representation.
Furthermore, the increase in type 2 diabetes among adolescents, particularly noticeable in wealthier nations, is of considerable concern, since as Dr Green notes "it is unclear whether findings obtained from trials of adults with diabetes are readily translatable to paediatric/adolescent populations".
And despite the fact that nearly 20 percent of adults worldwide aged 65 years and over have diabetes, less than 1 percent of trials specifically targeted this age group, while 31 percent actually excluded patients over 65 years and almost all excluded those over 75 years.
"Only a tiny proportion of the trials analysed-1.4 percent-listed primary outcomes including mortality or clinically significant cardiovascular complications," Dr Green said.
"Furthermore, distribution of registered trials by country does not reliably correlate with diabetes prevalence," she added.
The research is published in Diabetologia, the journal of the European Association for the Study of Diabetes (EASD).