I used to love making my own jam when I had a garden with fruit trees, bushes and plants.
There are recipes for low carb type jams that use alternative low carb diabetic friendly sweeteners (e.g. erythritol, stevia) and as you probably know some fruits, particularly citrus ones, are naturally high in pectin. So you have the basics there, and there are other, optional thickeners - I think some one on the forum has used chia seeds and I found a
quick and easy recipe for strawberry jam which uses glucomannan aka Konjac powder. So you can make jam that's both diabetic friendly
and "finger lickin ' good"!
Robbity