Databases and diabetes
The first step in the search for information is generally to access information collected, presented and analysed in an objective structured manner. The Cochrane Database of Systematic Reviews is a good starting point as it contains high quality reviews. Its reviews are mostly of interventions, but it is currently expanding to include diagnostics reviews. However, you should be aware that a high proportion of studies have been excluded because they do not meet the eligibility criteria. This is because Cochrane reviews are mostly limited to RCTs as evidence of efficacy. Another source is the Centre for Reviews and Dissemination (CRD) databases, funded by the UK government and freely accessible. Information concerning all ongoing or completed registered clinical trials can be obtained from the WHO International Clinical Trials Registry Portal or from the US government site ClinicalTrials.gov. Data concerning preliminary results from ongoing studies can be obtained by accessing abstracts of oral or poster presentations at scientific meetings, although these have not undergone full peer review. This section offers guidance as to how to access information from any of these sources.
Cochrane Database of Systematic Reviews (CDSR) on the Cochrane Library
The Cochrane Library is a collection of six databases that contain different types of high-quality, independent evidence to inform healthcare decision-making.
A key database is the Cochrane Database of Systematic Reviews (CDSR), a leading resource for systematic reviews in health care. The CDSR includes all Cochrane Reviews prepared by the The Cochrane Collaboration. Each Cochrane Review is a peer-reviewed systematic review that has been prepared by a group of reviewers, supervised by a Cochrane Review Group. As of March 2013, the CDSR included 5449 systematic reviews.
Reviews on diabetic topics are usually the responsibility of the Cochrane Metabolic and Endocrine Disorders (CMED) – see section on CMED. Some are looked after by other groups such Cochrane Pregnancy and Childbirth Group and the Cochrane Eyes and Vision Group.
Access to the Cochrane Library
Free online access is available in most low- and middle-income countries, and other countries provide access via national funded licenses via IP recognition. Click here for details of which countries have free access to the Cochrane Library.
Cochrane reviews are indexed in PubMed, but to access the full text you will need to go directly to the Cochrane Library to download it. This is because PubMed does not tag them as ‘Free full text available’ because the Cochrane Library is not freely available in all countries.
How to search
- Browse the systematic reviews on diabetes by going to the Browse by Topics option from the Cochrane Library home page and clicking on Endocrine and Metabolic and then Diabetes, or
- Search the Cochrane Library using a Simple Search from the home page or a more Advance Search option is available which provides you with an option of search limits to refine your search, and a search tab to View Search Tips.
Note: Results will be displayed records for all sections of the database but you can limit to just viewing Cochrane Reviews by clicking on the link in the left column under All Results.
The CRD Databases (Centre for Reviews and Dissemination, University of York) are funded by the UK Government and are freely available to all. The three databases, DARE, HTA and NHS EED, provide access to quality assessed systematic reviews and economic evaluations, and summaries of health technology assessments and Cochrane reviews
- Database of Abstracts of Reviews of Effects (DARE) is focused primarily on systematic reviews that evaluate the effects of health care interventions and the delivery and organisation of health services.
- NHS Economic Evaluation Database ( NHS EED) focuses primarily on the economic evaluation of health care interventions and aims to help decision makers interpret an increasingly complex and technical literature.
- Health Technology Assessment (HTA) Database includes completed and ongoing health technology assessments from around the world. It is a valuable source for identifying studies that have not been published in the usual places, like journals (known as grey literature) as much of the information it contains is generally only available directly from individual funding agencies.
How to search
From the CRD databases search page you have the option of choosing a Quick search or an Advanced Search where there are options to refine your search, including limiting to a particular database. There is also a more detailed Guide to Searching.
Clinical trials databases
Clinical trials registration can help improve clinical trial transparency and reduce publication bias and selective reporting. The WHO (World Health Organisation) considers that “The registration of all interventional trials is a scientific, ethical and moral responsibility”. Some journals require, as a condition of consideration for publication, registration in a public trials registry.
How to search
A key source of clinical trials is ClinicalTrials.gov. It is a registry and results database of publicly and privately supported clinical studies of human participants conducted around the world.
A number of other databases contain ongoing clinical trials. The WHO International Clinical Trials Registry Portal (ICTRP) provides access to these via a searchable database containing the trial registration data sets made available by trial registries around the world meeting criteria for content and quality control.
The ICTRP Search Portal is not itself a clinical trials registry, but aims to provide a single point of access to information about ongoing and completed clinical trials. To facilitate the unique identification of trials, the Search Portal groups together multiple records about the same trial.
Researchers often present new results at meetings, especially for large RCTs, prior to being written up for full publication in a journal. Also, it has been estimated that less than half of all studies, and only about 60% of randomized or controlled clinical trials, initially presented as summaries or abstracts at professional meetings, are subsequently published as peer-reviewed journal articles, and even those that are published may take years to appear. So, searching conference abstracts (or grey literature) can be useful if you need to do a comprehensive search and/or are looking for the latest data e.g. for the latest trial results.
Two main sources of diabetes conference abstracts are listed below.
- The American Diabetes Association (ADA) provides a list of Scientific Sessions for the annual meetings each June. Users can search the abstracts and webcasts (using an Advanced Search) for each annual scientific session going back to 2004.
The abstracts presented at the annual ADA meetings appear also in the June supplement (freely available) of the journal Diabetes (but they are not indexed in PubMed).
- The European Association for the Study of Diabetes (EASD) meeting abstracts provides a list of searchable abstracts (also with an Advanced Search tool) for the annual meetings back to 2001 and webcasts back to 2008.
The abstracts presented also appear in an annual supplement of Diabetologia (but are not indexed in PubMed).