The purpose of this study is to learn more about how U500 regular insulin can be effectively be used to treat type 2 diabetes. Most insulin treated patients with type 2 diabetes take U100 insulin, but if they require large doses (such as >150 units a day) they may experience pain at this site of injection and the absorption of the insulin is unpredictable, thereby leading to poor glucose control. To overcome these problems, doctors sometimes switch to a more concentrated form of insulin called U500 insulin. U500 is five times as concentrated as U100 insulin and therefore delivers an equivalent dose of insulin in much lesser volume. However, how to best use U-500 insulin is not certain. The investigators are not really sure how long a given dose is effective in patients who require large doses (>150 units of U100 insulin), so are not sure of how often the drug should be administered. In this study, the investigators will determine how effective two different doses of U-500 regular insulin (100 U and 200 U) are in lowering blood sugar and how long these two doses last. This information will help doctors develop better treatment plans for patients with type 2 diabetes.