But it seems that at least one pharmaceutical company may have figured out a way around that.
Oramed Announces Positive Top-Line Results from Phase IIb Oral Insulin Study
This US based double blind, 28 day, randomized study of 180 adult type 2 diabetic patients showed a statistically significant decrease in the primary endpoint, pooled night-time glucose mean percentage change of 6.47% from run-in, between placebo and active cohorts (p=0.0268). The study additionally demonstrated a good safety profile with no drug related serious adverse events.
As of right now, the oral insulin is only for those with type 2 diabetes, so type 1s (like me) can't benefit. This makes sense if you think about it, though, because type 2 diabetics usually just need a small boost of insulin to help their body's own insulin control their sugars. My body, on the other hand, doesn't make insulin at all, so I have to take an amount that varies every day, depending on what I eat and when. Oral insulin would likely take too long to take effect the same way an injection does, and it would be difficult to manage wildly varying dosages.
The trial drug passed Phase II testing and is currently going into Phase III. In other words, it'll still be a very long time before anyone (who isn't part of the trials) can benefit from this invention, but hope is on the horizon for type 2 diabetics who have difficulty with injections.