From IMDb.com:

Furst publicly credits J. Michael Straczynski's show Babylon 5 (1994) with saving his life, because he is a longtime diabetic whose kidneys failed midway through the show. A fan who loved his portrayal of 'Vir' heard of his health problems and donated a kidney to save him from dialysis and a likely early demise.

So basically a fan gave him another 20 years of life!