Calories burned is good but the best thing is the actual physical exercise itself. (For Type 2's) Using muscles enhances their ability to use your own body's insulin to move glucose into the cells for the mitochondria to use to produce energy. This is why you will often feel that you have more energy when you exercise regularly. YOU ACTUALLY DO!
Some people walk and other run, I swim for 1/2 hour. On a good day I can get in 1/2 mile but on a not so good day I may only get 1/3 or 1/4 mile. No matter what, (or how slow I am) I still try to keep moving for 1/2 hour. That's the key. Move for 1/2 hour. If you get a feeling of accomplishment from running then do it. You go girl! You probably are using more calories so you will lose a bit more weight. That is good. But if you only move and maintain your weight, that is good also. The secret is to move!
Try to do what isn't totally boring and something you can keep with over the long haul. If it's torture you may not stick with it. If you love it, do more of it! Just watch your sugars so they don't go too low. The good results of exercise can take hours to show up each day. You may find it better to have breakfast, do a 1/2 hour run, then do another one after lunch. That way you are moving the glucose into the muscles and using the calories you consume before they have a chance to be converted into fat. This is what medications do and by substituting exercise you will possibly stay off meds longer. KOKO! (Keep on keepin' on!)
"People are like stained glass windows: They sparkle and shine when the sun's out, but when the darkness sets in, their true beauty is revealed only if there is light within."
- Elizabeth Kubler-Ross