I had a BMI of 40 when I was approved for the DS--and when I actually had surgery I was at a BMI of 38. We have plenty of light weight DSrs and it's absolutely untrue that it's a surgery reserved only for the super morbidly obese. As long as you meet the nationally accepted standards for bariatric surgery, you can have the DS. Regarding the RNY, many people with the RNY end up overeating because they either don't dump (not everyone does) or because they become reactive hypoglycemic and need to eat right away after the food has pushed it's way through that stoma. They HAVE to eat in order to raise their blood sugar levels. With the DS, as long as you stay away from most carbs (or limit them severely), you can eat lots and lots of protein and lots and lots of fat. Only 20% of fats are absorbed and many of us need to eat enormous amounts in order to keep our stool soft enough to poop. Most DSrs eat way more than the average person. You're limited by the size of your stomach (mine feels TINY!) but the most important thing with the DS is to make sure you get 100 g or protein at least a day. So you're either drinking shakes or eating foods that are high protein to get the minimum in. For dinner tonight I had an egg (my tummy is still TINY) with extra thick bacon mixed in and lots and lots of cheese mixed in. On New Year's eve, I had 1/4 of a crab cake (it was all I could eat), half hour later I had part of a lobster SOAKED in butter. I did not feel deprived. But with the RNY, you'd be in some serious trouble with all of that fat. If you ask around, many people who've gotten the DS will say that one of the reasons they chose it was because it allowed much more opportunity to eat like a normal person and yet not gain the weight back. No surgery is a sure thing and one can gain back weight with any of them. With the ds, if you fill up on carbs instead of protein, you'll gain back the weight--or at least some of it. But if you're filling up on protein first, you'll only have room for very few carbs and then you're pretty much eating how you'd want. As a Type 1 or 2 diabetic, you are supposed to be avoiding carbs anyway so it shouldn't be too much of a lifestyle change from what you need to be doing anyway.
Also, the malabsorption with the RNY pretty much disappears after the first 2 years or so so you're more likely to gain back your weight. This isn't the case with the DS--the malabsorption doesn't go away--therefore there must be a lifelong commitment to taking vitamins, meeting protein requirements, and getting enough fat into your diet. I love hearing about how DSrs eat. It sounds like a lot of fun. Their slogan is always, "Bacon makes everything better!" Or, "Just add some heavy cream to it!"
Just give it some thought and do LOTS of research about the benefits and draw backs of the RNY. We have SO many RNY to DS revisions on the other board that I'd NEVER consider the RNY.
Oh and as far as the risks regardng doing the DS on a lightweight such as myself (or you), these were my surgeon's exact words,"I wish I had more patients like you. You're BMI isn't out of control, you're pretty fit and can move around well so healing will be better, and your younger (I'm 37). I wish I had more HEALTHY patients come in here for surgery like you." He made no mention of more risk with the lower BMI. Infact, he said it was BETTER.
Again, I wish you luck!