Case of Postprandial Glucose Monitoring

I think I am opening a pandora box but would like to hear other members opinions.
I have seen poorly controlled diabetics (with pre-meal Glucose values around 11-15 mmol/L) being told to do 2-hr postprandial Glucose by Glucometers (and as expected these values are around 14-18mmol/L). It's not that patient is doing this once a day at times they are told to do twice a day.
Now, Questions?
1. What are the indications of post-prandial Glucose monitoring?
2. What is the cost of one Glucometer reading? Is it worth the cost monitoring Postprandial Glucose levels in a patient whose pre-meal glucose levels are not under adequate control?
I don't really know the special significance of checking sugars two hours p.c. I ask poorly-controlled diabetics to check their sugars qid (A.M. fasting and any other three times, so long as the record the times clearly) and bring their logbooks in for me to review their numbers so I can get a feel for what's going on.
I don't know what a glucometer check costs. (D. Arnold)