It’s a numbers issue. From a small base, any rise is a large percentage. And in India the small bases are large in absolute numbers. So if you have 50M people in your middle class and they drink an increasing number of sugary drinks, the rate of diabetes can shoot up.
This is an unsubstantiated claim, see the comment above that referenced NIH studies discussing a genetic link between diabetes w.r.t. a subset of Indians.
