What are symptoms of diabetes in children

Hello, I have a son who is just shy of turning five years old. He suffers from mild hypotonia (muscle weakness) from an unknown cause.  He weighs 59.5 pounds and is only 40 inches tall.  For some time now doctors have told us that we really need to watch his weight and I have done everything.  I have already taken him to a nutritionist and she told us that we needed to decrease the amount of carbs in his diet (which we have) and other than that we are doing okay.  My son is a very active child, he does karate 3-4 times a week, has both physical therepy and occupational thereapy every week, and runs constantly at home.  I do notice that he drinks a lot, and after drinking any amount of fluids, he is going to the bathroom frequently, sometimes as much as every 15 minutes it seems- he is not completely potty-trained through the night so we have to special order diapers, and if we give him anything to drink after 7pm he usually wakes up to wet sheets (he has gone so much that he pee's out of the diaper).  

That said, an extended family member asked us if he had ever been tested for insulin resistance, which he hasn't.  I was just wondering if anything, in particular, that I wrote stands out to anyone.  I just want to make sure that we aren't missing anything that could compromise my sons health.  I thank you so much for taking the time to respond.

[JDRF-VOL-SG]

Type 2 diabetes is usually caused by insulin resistance, and being overweight is often the cause. The reason is that fat cells are insulin resistant and when a person, child or adult, has an excessive number of fat cells, insulin doesn't do its job as well to lower glucose levels. Diabetes can be the result. Type 2 diabetes in children is not common, but your family member does ask a good question, considering the thirst and frequent urination. If I were this child's parent, I believe that I would ask his doctor to check his sugar levels just to be safe. Do tell the doctor about the thirst and the frequent urination and ask him to check for insulin resistance.