Do you have a ketone meter or ketostix? Test him for ketones right away if you have a way to test.
Is he sick with something else? Sometimes, kids can have high blood sugars from illness.
I wouldn't mess around. I'd take him to a hospital. Kids can become very sick be in a life and death situation quickly.
Have you been to the Children With Diabetes forum? Go there and ask for advice. http://forums.childrenwithdiabetes.com/
Diabetes in children is nothing to mess around with. The sugar over 300 is very worrying.
Good luck. I'm sorry that you're going through this. I hope he doesn't have diabetes, but you can't take any chances.
He isn't producing any ketones, and the sick thing makes me feel a little better because he did have the flu about a week and a half ago. The on call doctor told me to watch his carbs until Monday. The 198 is the highest sugar I have had since I switched to sugar free juice and limited his carbs. I am trying not to be a psyco parent before monday so I just test his sugar if it seems like he is crabby and drinking a lot. My mom told me to do a fasting test to bring to the doctor, and his fasting was 138. It has just been a very long weekend!
I'll check back in to see how you're doing. The CWD forum I gave you the link for above is excellent. If your little guy does have T1, it will be an excellent resource for day-to-day management and to help you with support emotionally. There are several toddlers with T1 on the forum and there are also a number of parents who have T1 with T1 kids.
Take care of yourself. It ***** to wait to find out what's happening.
I'm new to this forum , but when I saw the subject line "21/2 year old, possible diabetes", it caught my attention, because our daughter (who is 8 now) was diagnosed with Type 1 3 months after her 2nd birthday. Please let us know what you found out at the doctor's this morning. I'm so sorry you are going through this. I can't imagine how scary it must be for you to think about your 2 y.o. having T1, since you are T1 yourself. A fasting blood sugar of 138 is high and a BS of 198 is high, even though it was after a meal. The fact that you have tested him and gotten numbers in the 200s and 300s is very concerning!
There are so many issues that are unique to managing a very young child with T1 diabetes. So, if that is the outcome (which I will be praying is NOT!), I would love to answer any questions and chat here with you about it anytime.