C.T.
Hi D. - if you are concerned about diabetes, then by all means you should take him to see his doctor asap. None of us can diagnose your son and therefore cant give you causes for his apparent infections or sleeplessness.
I hate to seem overly pragmatic but if you see a correlation with juice, then discontinue juice. Too much sugar intake without having diabetes can lead to all the symptoms you mention. Sugar can cause agitation and also provides yeast with their favorite food. Sugar also draws water into the bowel. His sleeplessness could even be caused by the pain of the irritation or bowel pain.
A quick way to know if he is spilling sugar or ketones (protein) into his urine as happens with diabetes is to purchase some of those indicator strips - you can find ones that detect sugar and protein on the same strip. You put the end of the stick into the urine stream and the paper on the end changes color. In 15 seconds, you compare it with a color chart on the bottle that shows you approx. levels of sugar or protein in the urine.
Even if the results are negative, you should still take him to see your doc so that they can evaluate him and run the tests necessary to diagnose him.