Maybe it’s because Americans are fat. Especially poor Americans who subsist on fast food and other junk. My guess would be that Indians in poverty are more likely starving than diabetic. Starving has its own health risks obviously, but being fat enough to impede your breathing isn’t one of them.
It appears that infection rates in India are low at the moment. It's not entirely clear why, but it could be a combination of hot weather, their nationally imposed lockdown, and lack of testing.