No argument on the press doing a piss-poor job of interpreting research results for the public, but the "broccoli" study (and studies about broccoli sprouts in general) is about isothiacyanates, something that's hardly present in "market stage" (i.e. the stuff you buy at the market). On top of that it comes from two compounds that react when cell walls are crushed - and one of those compounds is *very* heat sensitive.
There has been some interesting work with isothiacyanates, but mostly around removing cellular toxins like benzine (from air pollution - study done in China) and scizophrenia and ADD. The benzine is quantifiable via levels in urine, the 'mental' stuff more hazily with mental health professionals administering tests. Current hypothesis is that isothiacyanates trigger the SIRT system (mostly SIRT2).
I have seen nothing convincing with IR (or T2DM - for which IR seems to be a necessary precondition) and isothiacyanates, but if I was a researcher in either of those areas I'd want to test a hypothesis (AKA 'guess') that it might help. Gerry Shulman has shown in his NMR work that IR is cellular in origin (basically a triglyceride with one FA replaced with a hydroxyl jamming the series of reactions that starts with insulin at the bilayer and ends with GLUT4 receptors poking through. So why *wouldn't* activating SIRT2 help with that? Turns out it doesn't, but it's IMO a legit question to ask.
That said, was this study about fasting glucose levels (incipient T2DM) or glucose levels after a glucose 'challenge' (a GTT). From the numbers, it looks like fasting levels, so glucose release from the liver and not really about IR. Got a link to the study - not the press' interpretation of it? :-)