In recent years there has been a significant expansion of information and advice for people with diabetes available on the Internet. Interestingly much of this is provided by lay people, who often have diabetes themselves. Consequently we decided to critically evaluate the quality of non-professional advice available on the Internet for people with diabetes. This was undertaken by identifying a dedicated diabetes newsgroup, which was analysed by a panel of specialist diabetologists who assessed the quality of postings and responses using a six point classification. Each message was rated independently by each of the five panel members and scores were compared for reliability of judgement. From the newsgroup used mainly by non-professionals 61 start messages comprised 54 questions, six statements and one commercial proposition. Sixteen questions related to diet, nine to glycaemic control and blood tests, ten to tablets and insulin, eight to complications, and there were 18 others. 61 start messages were categorised as four excellent, 24 less good - some details, 17 poor - little detail, 17 vague, but none were misleading or incomprehensible. After 5 days 61 messages had generated 242 responses, which were assessed as 13 evidence based excellent, 60 accepted wisdom, 137 personal opinion anecdote, 26 misleading or irrelevant, one false and five open to misinterpretation. There were 146 respondents (30 more than once), range of replies 1-15, identified as a doctor in four instances, but usually patient, relative or unknown. Newsgroups such as the one we analysed are clearly a valuable forum for persons with diabetes to interact with each other, share experiences and provide social support. For the most part the level of understanding about the condition was quite extensive, with the debate being largely technical in nature. Of the 242 responses, only six were regarded as either false or possibly dangerous. This raises important questions about how to ensure that the information provided on the Internet for persons with diabetes is accurate, sensible, evidence based and easily accessible. Copyright © 2002 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]