"genetic predisposition"? Diabetes, even in humans, is at its root, a genetic predisposition, per subject. I see your quibble point though.... you seem to want to naysay all studies until they involve humans in front of you. Of course to save money and time, many animal studies speed it up with animals designed to more readily be afflicted with disease being studied. You can buy a wide range of lab animals prone to certain conditions, with cancer animals being a major one. In time, the papers citing diabetes surgery on aged rhesus macaques will appear, I predict, the gold standard animal, and large enough for precision surgeries. Instead of forcing a selectively bred rhesus macaque pron to diabetes, it seems 9 out of 12 OBESE age 10 rhesus monkeys were naturally diabetic in one study, and raised in private cages. With a number as high as 9 in 12 seniors tilting to diabetes, it seems the darling animal of science, can be cheaply obtained by buying the supply of preexisting fat old monkeys, rather than waiting 10 years to appease you and your doubting. I say that because you seem to be "species triggered" at the mice used in my first link. Natural occurring diabetes is high in old fat rhesus macaques, and provides ample test subjects to avoid a human trial to appease you. A human trial would also have to let the patient know that its only a 6 month cure anyways.