My fasting blood sugar is 6.5.Is this too high? I am not diabetic. Can this be a cause for weight loss.

Question not clear. Do you mean 65 or 6.5? If it is 65, it is borderline low; usually this level does not cause any symptoms. If it is 6.5, it does not make sense. It is too low and this level should cause severe symptoms such as confusion, agitation or even coma in most patients.