In the 80% or so of those who are cured of diabetes shortly after RNY gastric bypass and long before significant weight loss:
Could at least part of the explanation be that in these patients, a high level of constitutive gluconeogenesis was occurring in their duodena or a key regulatory/stimulatory event in gluconeogenesis, or both?
At any rate, causation is out of the question. Causation is an over-used, inane, insane function of one variable.
Enough gluconeogenesis to account for most of the excess glucose found in their bloodstream after an overnight fast?
At any rate, more gluconeogenesis than is commonly recognized. Doctors believe that in general the liver does most of the gluconeogenesis, followed by the kidneys, followed by the intestines. Perhaps in most healthy individuals and when gluconeogenesis is not constitutive.
But in everyone else? I doubt it.