Hi I Have A Son Who Is 2yrs Old And

Hi I have a son who is 2yrs old and he a problem of pee out too much every hour only after consumption of any kind of sweet or fruits. If I give him any fruit at 11.00 am then by 2.00pm he starts to pee in large quantity with the urine being clear like water and then he pees again around 2.30pm or 3.00pm. And then he does this again after an half an hour or 1 hr and then his urine frequency becomes normal. this happen with any kind of fruits or sugar or jaggery or honey. He is facing this from past 5 months and I have learnt that by eliminating all the sweets or fruits from his diet his urine frequency is jst 6 to 7 times in a day. He doesn't complain of pain or burning sensation while urinating.. have got his blood sugar checked and it is 77mg/dl. Have done urine analysis also and there is no glucose in the urine and all his scan reports all normal.. am completely upset with the situation and I don't know what's going on need some help