To comprehend the aversion to diabetes in geese we first need to recognize causes of diabetes. Type 2 diabetes is more prevalent in older and/or obese humans. Geese, by genetics, cannot become obese! BAM, one down… Old geese? The goose physiology is, obviously, completely different from humans and do not push the age of their body beyond natural means through medicine therefore the problem of being venerable in geese is nil. Many other sources will cite inactivity as a cause of diabetes to which any observer can empirically discover geese avoid.

Honey Nut Cheerios: May cause diabetes in geese… when eaten in excess

Another more commonly accepted and widely understood cause of diabetes, both types, is genetics. The genetic history of geese does not include diabetes. In fact, the genetic make-up of geese is quite healthy and includes few genetic faults.

French: May cause diabetes in geese.
and probably do

To encounter any true “cause” of diabetes in geese you can look to one place, one race, one location: France. The French enjoy goose liver, what’d you expect? They’re French. To this end they force-feed geese to enlarge their livers. This causes heart disease, obesity, and high cholesterol in the geese. Two of these are prime causes of diabetes. Furthermore, this can, on occasion, cause hypertension, another major cause. Unless the French cause the geese to become “Hispanic, black, Native American, or Asian” they can’t increase the geese’s odds of contracting diabetes any more. (Quick, put those racist fingers away, the list of races in the previous sentence is a direct quote from WebMD).

Worried about the geese? Yell at the French or quit shooting them (the geese not the French).

Sources include:
National Diabetes Clearinghouse
Why Geese Don’t Get Obese (And We Do) by Eric P. Widmaier