Loved Sioux falls!! I happened to be there over Thanksgiving. The holiday parade is a must!!!!!
The glycemic index is really a measure of how quick foods are absorbed and transformed into blood glucose levels. This has been useful for diabetic patients to help control their blood glucose range, and lately, has been seen to get beneficial for losing weight.
I lived in Sioux Falls for awhile. If you're looking for locals, head to Nutty's Pub & Grill. Falls Park is also an interesting spot to visit. (Although on an off day, with the wind blowing the wrong way, you'll likely get a whiff of the nearby cattle packing plant north of the park.)
Unless you have business here, there isn't any real need to stop. Nothing much to see or do, although it is a nice enough town with friendly Midwestern people.