You are admitting someone with type 2 diabetes and they come from home with a slew of the oral hypoglycemics - the metformin, sulfonylureas, whatever. You can't quite remember which one might cause lactic acidosis or which might drop someone into hypoglycemia.
Here's what you do: stop all of those drugs. Write on the orders for four glucose checks, and then write this chart:
<150 - no insulin
150-200 - 3 units
200-250 - 5 units
250-300 - 8 units
300-350 - 10 units
350-400 - 12 units
>400 - call physician
Your ward or ER might even have a stamp with this on it or a pre-printed sheet.
If you do a search on "sliding scale insulin" - you'll see that this approach is on the way out, considered bad by the experts because it "chases after glucose levels" rather than trying to keep them even. Your hospital MIGHT have a better protocol, but there isn't a standard one out there. And your goal is not, at this point, perfect glycemic control, but rather to not kill a patient. Most senior doctors trained with this kind of treatment. If your hospital has a better system or even a computerized one, or an endocrinologist who is interested in the subject, great. In fact, please share. But if not, you won't kill someone like this.