Bearing in mind that I am not qualified to comment, I would suggest you have a good look at this website
http://www.bloodsugar101.com
It shows what is normal blood glucose and how, and why, it goes wrong
There is masses of info there
To my very limited knowledge / viewpoint, the results in Test 1 show a fasting BG in the normal range (I envy them), and on the lower side of normal too. Suggesting that the body produces enough 'background insulin' to keep nicely in the healthy range.
Tests 2 & 3 seem to show results that are slowly transitioning into diabetes (assuming they are all from the same person?
On the other hand, Test 4 shows a delayed response to drinking the glucose. The BG drops too low at 270 mins, (into the hypo range, I think). Probably the body over-reacting to the high.
Since they are over 11 at 2 hours, the results count as diabetic.
I may not have much medical knowledge, or experience at interpreting OGTT tests, but I have a lifetime of learning how to avoid that low you got at 270 mins! And for me, the answer is to avoid eating anything that takes me high (sugar, bread, rice, pasta, potato, crackers...) because the inevitable result is that afterwards I will drop down too far. It is like a bouncing ball - go too high, and it WILL go too low. Far better to avoid both the high AND the low by eating a diet that keeps BG steady.
Hope that helps.
Are the results all from the same person?
And over what time period were they taken?
And what happens to the fasting BG over this time period?
And please, people, if I've given out any wrong info, forgive my ignorance, and set me right...?