Who knows about the ants, even though they are sometimes attracted to sugar. The real questions are: Is he urinating often, and more volume than you might expect? Is he very thirsty? If the answer to either of these is yes, make sure the doctor tests him, preferably with a better test than a 'spot' blood glucose. And if he isn't diabetic, then ask if the doctor thinks there is any problem causing him to weigh less than expected.
Thanks for your response.
I got my son checked by Doctor. He did urine tests for sugar, ketones etc., Fortunately, there were no trace of sugar and ketones. Based on this, Doctor has ruled out any diabetes.
Appreciate your active participation in this forum.