At Three Years, Gastric Bypass Superior to Intensive Medical Therapy for Obese Type 2 Diabetes

…in terms of weight loss, lowering of HgbA1c, and weight-related quality of life. The specific gastric bypass surgery used in the study is the Roux-en-Y version.

Band Gastric Bypass Surgery (not the only type of gastric bypass): very successful at “curing” T2 diabetes if you survive the operation

Average initial weight of participants was 104 kg (229 lb). Bypass patients dropped their weight by 25 kg (55 lb)and HgbA1c decreased by 1.8% (absolute decrease), compared to intensive medical management participants who lost 10.3 kg (32 lb) and dropped HgbA1c only by 0.4%.

I doubt that intensive medical therapy included a low-carb Mediterranean or paleo diet.

Source: Clinical and Patient-Centered Outcomes in Obese Patients With Type 2 Diabetes 3 Years After Randomization to Roux-en-Y Gastric Bypass Surgery Versus Intensive Lifestyle Management: The SLIMM-T2D Study | Diabetes Care