The DS is no longer reserved for higher BMI's. There are a LOT of lightweights, BMI 35-40 that have had the DS and do very well. A DS surgeon can adjust the stomach size and length of the common channel to be appropriate for lightweight patients.
They have been doing the intestinal portion only on normal weight people in Europe for over 20 years to cure Type II diabetes. My diabetes was resolved the day of surgery. My blood sugars went to normal and have stayed there for 8 1/2 years.