I don't think is true. Debka appears to be referring to Muhammed Butt, and he was reported to have died of a heart attack.
Now the official report might have been false (I have no idea), but it's not correct to say that a name and cause of death were not released. As things stand, though, I just don't believe Debka on this. (Is there really any evidence that he died of leukemia, or did Debka just say that?)
Of course, if there's a second person, other than Butt, who died anonymously in custody after showing symptoms of gingivitis, that would be interesting.