Diabetic lipohypertrophy on abdomen for 20+ years (Photo)

Seems a panniculectomy is ideal surgery in your case; avoids the costs and invasiveness of a full tummy tuck and still gets rid of the hanging apron. However if you wish a full tummy tuck you can also opt for it should you wish to threat the upper abdomen as well.See the link below to find few cases of my own practice very similar to yours which I had the opportunity to operate successfully on, sharing a lot of common features with the technical problem you have posted.
If you wish better grounded opinion well lit, focused and standard images have to be assessed: frontal, both lateral and both oblique views, also from underneath.
Feel free to request any additional information from me.

Thanks for your question and photos.
From your photos and history it looks like you would certainly be a candidate for contouring of the abdomen.  There are a multitude of options available.  From non-invasive techniques such as CoolSculpting all the way to formal surgery.  Liposuction is a very powerful tool when it comes to removing stubborn fat.  The one caveat to consider is the contour following liposuction.  While very good at removing the fat it has a small to moderate effect in tightening the skin.  You may want to consider an adjunct to liposuction such as BodyTite or even consider a formal skin excision (mini tummy tuck) as part of the procedure.
I would recommend you have a consultation with a plastic surgeon who has multiple options available.  This way the best option for your particular body and concerns can be selected.
Best wishes.