http://www.alz.org/national/documents/topicsheet_diabetes.pd...
The order of causation may be the other way around for whatever association there is between diabetes and Alzheimer disease, if a hypothesis about a genetic variant in insulin processing related to Alzheimer disease holds up.
http://www.bbc.co.uk/news/health-18445701
But right now it is much too early to say yes to to the question posed in the headline of the submitted article. The underlying study
http://www.ncbi.nlm.nih.gov/pubmed/22810099
has several desirable design features for a human nutrition study, but it still needs to be replicated, and it's an observational study, not an experimental study, so we don't know what kinds of interventions are likely to be of most help in preventing Alzheimer disease.
http://norvig.com/experiment-design.html
See another thread just posted by another HN participant
http://news.ycombinator.com/item?id=4578600
about how rarely supposed breakthrough medical discoveries are even replicated. Don't believe the easy, breakthrough answers until they have been verified.
AFTER EDIT:
The comment responding to my The New York Times recently seems to be willing to give up its journalistic reputation in the medical stories on its hosted blogs and go straight for eyeballs at any price in credibility is of course correct that the New York Times has disclosed that the writer is writing as a blogger, not as a journalist. I think it's regrettable that he nonetheless is able to slap the New York Times brand on an overly speculative post that assumes matters of fact that are not well verified. I'm not sure if all readers are as aware as many HN participants that some long-established journalistic organizations host blogging webpages that have no editorial oversight. I think it would be helpful for readers to be able to distinguish at a glance what sources are professionally edited, and which are people doing their own personal expressions of opinion.