I just read both and I'm not sure I understand what your point is here. I don't have much to say about the diabetes page other than there is some interesting (as well as unfortunate) information. The HIV page certainly doesn't seem as if it gives off the "not a bad disease" feeling. It lists an untreated life expectancy as 11 years, whereas the diabetes page lists an expected life expectancy of being reduced by 10 years. That certainly makes HIV more deadly. It's also made obvious that it's transmissible from normal sexual behavior, as well as being so for some time before one would even experience symptoms. It's definitely not a bed time story. If anything, I'd say the diabetes page is less scary in its overall presentation than it should be.

Obviously this is subjective. I'm not saying you're wrong, just genuinely curious at what made you think this. I'm not making assumptions, but perhaps you have (unfortunately) more personal and upsetting experiences with HIV/AIDS than with diabetes? I know that when I used to bartend at a neighborhood gay bar frequented by gen Xers it was very difficult to see and hear people lose or talk about losing their partners to something that alienated them even more than they already are/were.

It is interesting to think about how to convey information about these things though. I think it's probably a good thing to make HIV/AIDS not sound so terrifying. For pretty much every adult alive today, I'd assume, their idea of HIV/AIDS was something like being told it's a "gay disease" or that you can't touch people with it (thank you for your service, princess Diana) or some sort of anti-African racist nonsense. So conveying accurate information without bigotry, homophobia, or xenophobia is probably a good thing overall.

Also curious what sort of possible conspiracy would benefit from Wikipedia readers from not being more afraid of HIV/AIDS.