What the heck is this metformin stuff, and how is it slowing aging?

So I'm sitting here watching the Q Exactive blow away yet another triple quad (the Q E is like "what's a matrix effect? never heard of it...") in terms of small molecule sensitivity and I have some time to browse Twitter and I see this article from June!  What the Albert heck is this about?  (Shoutout to @attilacordas for the Tweet)

Human beings are being given an Anti-aging drug? Sign me up!  Turns out you have to be suffering from one of three conditions to be eligible - cancer, heart disease, or cognitive impairment. You might argue I qualify under the third condition, but I think they mean decline from baseline and I've always been this way. The drug they are testing is metformin.

Next question is the title of this post. What does this stuff do?

Well, Chengkai Dai says its something like this (in this here paper):

In this paper he argues that HSF1 is repressed by nutrient stress and/or metformin and induces "proteomic chaos" and this messes up tumors. Which sounds pretty awesome. But what does this have to do with aging?

Time to turn off the "since 2015" filter on Google Scholar and travel far, far back in time!

So, this group dosed worms with the drug and did 2D-DIGE and peptide mass fingerprinting to come up with the solution that its all about reactive oxygen species and peroxiredoxin.

Which sounds an awful lot like what the resveratrol people have been thinking their drug does...either way this is super cool.