Aha - another treadmill lover. It really does work to lower the BG but I try not to get in the habit of doing bad and then repenting on the treadmill! That being said, it is nice to know that you can help yourself recover. Several times, my husband and I have gone out to eat and afterward I have insisted that we walk around the parking lot or a little park nearby before getting into the car for the drive home. The only time I have been able to lose weight is when I go for a walk after dinner.
I generally walk at least a mile a day. If I do more it is in a second session. I walk at three miles an hour at an incline that works for me.
The TV where my treadmill is located doesn't have cable so I rarely watch it - I'm a news junkie. I like talk radio but the motor of the treadmill interferes with AM. Now I listen to my discman - at present I'm hooked on an old Mark Knofler (sp?) disc. The songs I like have a perfect 3 mph beat! I can't listen to a TV or radio in the room - it has to be headphones straight to the brain or I get so bored I could scream.
I would love to be able to read while walking but it just doen't work for me. I can't get the bifocals set right. I haven't tried talking books, but that might be interesting.
I've been doing this for a little over a year and haven't noticed that I have to go farther for the same results. I guess if that did happen you could just up the incline a little - more workout in the same time.