I've added a link at the bottom of HubMed searches to send the search to Google Scholar, Google's new search engine/citation database for academic literature.
While Google Scholar does - vaguely - allow you to limit searches to abstracts in PubMed (there are still some links to other NCBI pages mixed in), the number of results is much lower (141,000 for an example search for diabetes) than using the full PubMed database (209,520 for the same example).
A specialised search, limited only to MEDLINE abstracts but using Google's ranking algorithms, would be ideal - this kind of relevance ranked search has been impossible since BioMedNet closed its MEDLINE service earlier this year.