As a non diabetic, (ahem!)
I would like to point out that achieving a normal blood glucose level in the fives permanently is possible. I am there, and I know when my levels are slightly higher.
And as a non d, my levels would rocket to the mid teens, even on a low GI diet, from being in the normal range before the meal. However, after two hours I would be in high single numbers, then by three into normal range. By four hours, I would be really hypo. Weirdness!
To me your Hba1c is what most doctors go by. And this is the basis along with fasting % glucose is the norm by how T2 is diagnosed.
Depending on your insulin resistance and how susceptible you are to certain foods dictates your treatment. The amount of insulin and other hormones is ignored in determining diagnosis. This is not only totally wrong but ignorance in the medical industry.
As everyone on here knows, diet is the key to getting your blood glucose levels and your insulin resistance down, which has a huge effect on weight loss and control of diabetes.
Getting your bloods in the normal range as often as possible, will lead to better health management.
So to generalise, is to err for those, who have sharp spikes and assume we are diabetic because of high numbers after two hours. It again depends on how we tolerate foods and how slowly we digest and of course get our bloods down