Go, Read: Frank Miller Profile Contains Neal Adams' Appraisal Of Miller's Poor-Health Period
Here. Sam Thielman does a good job of balancing Miller's more obtuse references to absence from his own life with Neal Adams more directed advice to indicate there was some heavy drinking during a recent phase of Miller's career. I don't know that I've seen this discussed with someone with direct knowledge in a public way yet, although it was certainly the driver of a thousand convention conversations.
It's good to know that Miller survived at least one friend's expectation of his passing, and would seem to believe himself on the mend. I hope one day he can better and with more focus engage with the work he did he doesn't feel he could do now, and understand that reaction to him will be shaped by that work.