Felix has been getting potato flakes in his regular food when I need to steer him a bit. He doesn't come up as high as with honey, but it does last longer (two hours or more). I still use honey if he goes below 50--or I'll put in both potato flakes and honey, which he thinks is yummier than plain cat food. I usually start with 1/4 teaspoon in maybe a tablespoon of food, and I'd estimate that behaves like medium-carb for Felix. It takes some experimenting. I think Stacy & Asia has used rice flour, too.
Hope Jones is back to blue soon!