The American Diabetes Association has pretty good information. Here's a short article: http://www.diabetes.org/living-with-diabetes/treatment-and-care/bariatric-surgery.html
I also read their book: https://www.amazon.com/Things-About-Diabetes-Weight-Loss-Surgery/dp/1580406149
The American Society of Metabolic and Bariatric Surgery has a longer article: https://asmbs.org/patients/surgery-for-diabetes
If you're interested in wading through medical studies, I'm happy to point you at some. I know that isn't everyone's cup of tea, so I didn't want to start there. The short version of what studies are finding is that many people (above a BMI of 35) experience a very fast improvement, so quickly after surgery that the drop in body weight can't possibly be the cause. There are a lot of theories about what the cause is, but there are enough pieces of evidence both in favor of and against each of them that it seems like the best answer is "it's a variety of mechanisms."
No matter the reason, because of the speed of the change in people's diabetes after surgery, you might find that your current need for 100 grams of carbohydrates per day to keep your numbers stable may not be the case after surgery--almost certainly won't, in fact. (I'm not saying you will definitely be able to control your diabetes with diet alone -- it happens for some people, but some others are merely able to decrease their reliance on medications. Just, the things you know about your body will change.)
Someone posted the Kaiser Permanente list of post-surgery foods on here, not long ago, which I only remember because they were throwing carbs in there right away, where my surgeon's nutritionists are very focused on protein, then vegetables and fruits, and only much later carbs. So different places will have different rules, and if you want a look at that particular set, to see how it matches up with your needs (keeping in mind that those may change!), that might be worthwhile!
Anyway, best of luck in making your decision!