I m an underweight diabetic, i started exercising 3 days back, my bg was 375 on saturday n it's 334 today. is it good n will it get better further?

Exercise & diabetes: Presumably you have T2DM since you are on glipizide. Exercise is good, and usually helps lower blood glucose, both through weight loss, and through increasing muscle glucose usage. But exercise alone may not be enough to lower your blood glu values. Glu over 300 is very high, and it needs to be much better. See your doctor.