Is my Hamster sick? or does he have diabetes or something?

his big may be his testicles. my russian dwarf seems like he has a big puffy but its actually just his testes, when he walks it seems as if hes wearing a diaper because he waddles but thats normal. Another one of my hamsters also ran a lot and drank a lot of water. he also got very skinny and id notice thered be a bunch of fur near his running ball but he didnt look bald or anything. since your hamster is short lived, it will probably die soon, its a tough reality but it happens :/ its not rare for hamsters to have behavioral changes. however if this "big " of his was sudden like you said and noticeably red and has no fur on it, it may be a tumor.