Are you sure that it was the post 1 hour test that came back at 47 mg/dl and not the post 2 hour test? Bloodsugar levels will typically rise immediately after ingesting the glucose mixture before plummeting if you have reactive hypoglycemia.
Regardless, that test pretty clearly shows that you have reactive hypoglycemia - your body just releases too much insulin following the ingestion of high carbohydrate foods and drinks. The only way that I am aware to control this is to severly limit your intake of fast acting carbohydrates. Do a search on www.***********
for glycemic index. Foods high on the glycemic index result in rapid and significant bloodsugar rises which can trigger the release of large amounts of insulin. These foods are mainly sugars (candy, sweets, soft drinks, etc.) and starches (breads, rice, corn, wheat - most refined grains - and potatoes). If you select foods low on the glycemic index such as meats, eggs, cheese, green leafy vegetables, nuts, legumes, some beans, etc. you should be able to avoid the hypoglycemic reactions. Another thing to do is not eat large meals, but eat smaller and more frequent meals. Stay away from buffets - these will cause more harm than good - because if you are like me you want to get your moneys worth when you are there plus it is hard to avoid the breads and desserts.
You also mentioned hypertension. This can go hand in hand with high insulin levels commonly associated with reactive hypoglycemia and Type II diabetes. Yes, Type II diabetes. Reactive hypoglycemia can often result in Type II diabetes if you don't get it under control by limiting your intake of carbohydrates. Are you overweight or have abdominal obesity? These are also associated with high insulin levels. All of these symptoms can be grouped into what is called Syndrome X. You can do a search for that on google or here on Healthboards as well. Again, the key is to limit your intake of carbohydrates, especially the sugars and highly refined carbohydrates that trigger the insulin release, and increase your amount of exercise which helps to lower insulin and bloodsugar levels.