That's debatable. In the first example from the comparison site I used it showed a 14% uplift simply by ticking the diabetes box. But when it came to a full quote, that uplift disappeared. So as I said above, I can only conclude that they want to see badly managed diabetes (backed up by GP verified high HbA1c) to achieve an uplift. So it looks like typical marketing smoke & mirrors. Unfortunately the L&G quote I did didn't save to try amending & I CBA to go through it again.
As for duration, an annuity pays until death & isn't time limited. If you live longer than anticipated you win, & if not the provider wins.