That can be real, but there are some factors involved there too, which makes it more complicated.
With diabetes you often get diagnosed when it's basically too late. When you're already a fat blob, with a bad lifestyle, and probably unwilled to change it, which is making it worse (please note: I said often). Or you are willed to, but the process is extremely hart and requires discipline. Diabetes furthermore often comes with other comorbidities, like the mentioned obesity, which will increase your chance of heart attacks and other problems, like e.g. the diabetic feet.
With HIV you can get diagnosed when you have no disease symptoms yet, and treating it basically requires no effort from your side, besides regularly taking your medicine (although resistance can arise, making it again more dangerous). EDIT: Should be said that also HIV drugs have side effects, which will make life more annoying (like diarrhea and nausea), or which even could be very dangerous. Life long. So nothing to take easy, HIV is a very serious illness.
So for both you need to take life long medicine, but the former requires more effort, and you're probably in a worse state when you hear you have it.
I would still prefer diabetes over HIV. With diabetes you cannot potentially hurt your loved ones.