One would assume that the answer to this question is running.
However, I have found that yoga which moves rather quickly, such as Ashtanga yoga, actually lowers blood sugar more. This type of yoga is really fun and athletic and uses a lot of muscle power. When you exercise your muscles with yoga or lifting weights or doing callisthenic exercises, you are burning a lot of calories. Maybe not as many as running while you are doing the exercises, but using your muscles burns a lot of calories hours after you have used them!
I used to only run but, have now incorporated yoga into my workout routine. Just a few days a week keeps my need for insulin low. After doing an hour of yoga I can eat a small bowl of fruit or a piece of toast without giving an insulin shot.
And that makes me happy.
So try adding some resistence exercises to your routine like lifting weights, yoga, pilates, calisthenics, and see all it does for your blood sugar!