I am a healthy 16-year-old male. I am 5'7" and slightly light for my height; I would estimate my weight to be around 115 (although the number is quite static and I don't expect it to have changed much). All of my life, I have drank in considerable amounts. I would always say that my "mouth was dry" and that I needed some more fluid.
However, as of recently, I've seen slightly more foreboding symptoms. I easily drink over a gallon of water (via dissolved iced tea packets) a day. In turn, I also urinate very frequently, to the point where I may need to go twice within one hour. Not even that, I do not urinate completely; that is, I may go, and then without drinking or eating anything, have to go again not long after. However, both times, I urinate what I would deem to be a "normal" amount, surely enough to empty the bladder.
The major question mark, however, arises here: I have been tested before and was found to be negative. So, my paranoia-induced question is, essentially, this: can tests before some of the more prominent symptoms arise be false negatives? Do high blood sugar levels really exist before the bulk of the symptoms? If so, should I be tested again, or am I overreacting?