More than a quarter of posts on Facebook sites for people with diabetes are promotional, many touting products unapproved by the FDA, a study of diabetes-focused social networks says.

The study, in the Archives of Internal Medicine, looked at 15 sites found via a Google search. The sites varied widely, with membership ranging from 3,074 to more than 300,000 and diverse policies on advertising, sponsorship and membership, One policy uniting almost all of them: running industry advertising.

All but two sites required commenters to register, though many required minimal information, some only asking users for a handle and an email address. Only TuDiabetes (see Headliner, p. 34)“ required an extensive profile to be sent to the site administrator.” Physicians were on hand to answer questions on a third of the sites and more than half used diabetes educators to answer member questions, though those authorities systematically scanned posts on very few sites.

The study’s authors wrote that “little is known about the structure of communication, the sources of funding and the presence or use of advertising on these sites.”

“Existing sites differ in their approach toward communication structure, authenticity and quality oversight, expert participation and advertising or sources of funding,” said the report. “These metrics may be important to patients when selecting a community and may be of interest to health care providers who ultimately may advise patients about their particular needs.”