For normal folks, the blood sugar level rises rapidly after eating and peaks in about 30 minutes, then decreases gradually back to normal fasting levels (less than 100) within 2 hours. This is the reason for the testing at 2 hours after eating.
For folks with diabetes, the peak can be much higher than normal and the length of time for the bs level to decrease back to fasting levels can be much longer. Also if your fasting level is higher than normal -- your peak will tend to be higher and it will take longer to decrease.
What you are attempting to measure is how close to normal you are -- that is, how much under control your diabetes is. You are close, but still need to work on it.