I am an MD, but only an ER MD, so I don't deal with long term management of diabetes. The way I think about diabetes is this: the cells in your body need insulin in order to allow sugar to get inside. Your pancreas is designed to produce the insulin required. In type II diabetes, the pancreas is still producing insulin, but the amount produced is not enough. This is ususally for two reasons. The first is that usually type II is associated with being overweight. There are too many cells requiring insulin for the pancreas to keep up. Think about it this way: Say you build a sprinkler system for your yard. You don't have good water pressure, so you calculate the resistance in the pipes for your system, and you buy a pump for it. Then your neighbor decides to tap into your system one night to water his lawn. All of the sudden, the pump which was perfectly adequate for your yard can't keep up, and nobody has good pressure. Our bodies were designed to be within a certain weight range in order to function, and when they get outside this range things don't work right.
There is a second aspect as well. People with type II diabetes also have higher insulin resistance. This means that the receptors on their cells do not bind insulin as well as someone without diabetes (or they may bind the same but have less of an effect). The net result is that more insulin is required per cell than in a person without diabetes. As far as I know, noone is sure why this is. Almost all of the time, if the person loses weight and gets down around their ideal weight range they will no longer need medicines, as their pancreas will be able to keep up. I am not sure if the insulin resistance goes away, or if they just get to a level where the pancreas is able to produce enough insulin, but either way weight loss will usually cure diabetes.
As noted above, there are several different ways to fight the elevated blood sugar with diabetes. There are four basic strategies:
1. Lower peak glucose levels- these drugs (acarbose and miglitol) slow the rate at which your body absorbs sugars from your intestines. They decrease the "spike" of sugar which normally happens after eating, and kind of smooth it out to a more gentle curve. The thinking is that the pancreas can produce less insulin but over a longer time period to compensate. These drugs tend not to be very powerful, and only work with someone who has mild diabetes, or in combination with other meds.
2. Stimulate the pancreas to produce more insulin- (sulfonureas and meglitinides) These drugs stimulate the pancreas to produce more insulin. They are very successful- to a point. The pancreas can only be pushed so far, and eventually demand again outstips supply. These are the drugs used most commonly for type II diabetes.
3. Increase sensitivity of receptors to insulin- (Metformin and thizaolidinediones) These drugs make the receptors more sensitive to the available insulin. There were some problems with the first thizaolidinedione on the market, and it was pulled. This class is fairly new, and expensive, and I am not too familiar with it. Here again, the problem becomes that eventually the pancreas may not be able to keep up.
In managing type II diabetes, a Dr can use one or more of the above meds to try to lower levels. At some point, however, if you are unable to get sugars down, the final solution is to just inject insulin- supplementing what the pancreas makes.
Is there an advantage to using these drugs in combination with insulin? I am not sure that has been proven. It seems logical that if you are on one or more of these above drugs it will decrease the amount of insulin you need to inject, but I am not aware of any studies which show an advantage to this. However, I am not a primary care MD and am not up on this literature. I do know that the current trend is to use one or more of the above medicines in combination with insulin if the oral meds cannot manage the sugar alone.
In your case specifically- it is very important that you lower your sugars. Running in the 200s all the time is setting you up for some very bad things- loss of your vision from diabetic retinopathy, possible renal failure and the need for dialysis, and much higher risk of heart attack and stroke. It is VERY IMPORTANT that you get your sugars down even though you don't have symptoms. Talk this over with your MD and determine the strategy he/she has for controlling your diabetes, and keep at it until your sugars are in the normal range. It would make sense in my mind to add another oral medicine from another class and see what your sugars do. If this is not enough, then add a medicine from the third class. It will be much easier for you if you are able to control it with pills instead of going to shots. If the combinations do not work, then you may need insulin, but I don't think you have exhausted your other options yet. If your MD is not aggressive in trying to control you diabetes, find another one. You do not want to end up paralyzed from a stroke prematurely, or on dialysis because you waited too long. Hope this helps, and good luck. By the way, weight loss and exercise will help, but you need much better control right now.