I commented the changes I made to another commenter.
But regarding "feeling" when your blood sugar is high, I didn't feel it. However, I had symtoms of always urinating and really thirsty, my friend (diabetic) recognized the signs and tested me. It was 420.
Starting that day, I changed my life, hard.
To this day, I never "feel" my blood sugar fluctuate. I could get it up to 140, and down to 70, and I wouldn't be able to guess. I mean, I could guess by taking into account what I have eaten recently, but never based on "feeling" alone.
To a certain level you might not feel if your blood sugar is high or normal. But after 250 mg/dl, especially at 400 mg/dl you'll feel it. The most obvious symptom is fatigue and thirst, no matter how much you sleep you will feel exhausted all the time. You will want to drink a lot of water, you will urinate frequently. Your eyes will start to hurt. After being high for some time, your vision might get blurry, your eyes dry, you'll start vomiting.
Also you could smell your urine, if it stinks like ammonia, your blood sugar levels are high.
If your blood sugar levels are normal you feel healthy.
I've been a T1 since I was 10 and this is my experience. The real problem is not noticing highs but noticing lows. Because low blood sugar is much more threatening than highs for the short term.
But regarding "feeling" when your blood sugar is high, I didn't feel it. However, I had symtoms of always urinating and really thirsty, my friend (diabetic) recognized the signs and tested me. It was 420.
Starting that day, I changed my life, hard.
To this day, I never "feel" my blood sugar fluctuate. I could get it up to 140, and down to 70, and I wouldn't be able to guess. I mean, I could guess by taking into account what I have eaten recently, but never based on "feeling" alone.