Because people eat different types of diets and consume, for example, different ratios of omega fatty acids - which in turn can cause chronic inflammation and diabetes
I'm not disputing that people respond differently to sugar. I'm asking how that explains the diabetes epidemic becoming more and more widespread as time goes on.
I see. Diabetes is downstream from chronic inflammation, so something is causing us to be inflammated at scale and that is why diabetes is becoming more commonplace. So differing response to sugar is one factor of N possible affecting variables