Firstly, "linked to sugar" is not "squarely caused by sugar".

Secondly, sugar use is extremely widespread. Much more so than use of heroin. Few people avoid ingesting some sugar.

Even if there were 4 times as many deaths confirmed to be squarely caused by sugar, that alone shows sugar to be far safer, since it has far more than 4 times the users.

But never mind, let's look at, oh, the lethal dose (LD50) info. For sugar, that is supposedly something like 30 g/kg. The LD50 for heroin (intravenous) is something like 20 mg/kg: more than a thousand times less.

Plus there is copious sugar in your bloodstream without which you'd be in hypoglycemic shock leading to death.