Is anyone doing this regularly or even on occasion, and how much faster is the absorption rate? I had a coworker who said he did all his bolusing into the muscles in the back of his arms and he had not problems after like 20 years. Thoughts?
Dr. Bernstein recommends this technique for corrections (not for mealtime boluses). It does result in a fast onset and effect which is exactly what you want for correction. After all, why would you want to wait around to correct a high. He recommends using the deltoid (on your shoulder), but I just use my quads. I can then walk or run around to get it to act even faster. There used to be a video showing his technique, but sadly it is gone. Since I rarely correct, I don't do this very often, but it does work well. The only caution I would make is that you absolutely must know your ISF and not overbolus. Because of the fast onset if you take too much insulin the onset may be faster than your ability to eat glucose tabs to treat a low and that would be bad.
Bernstein uses a low carb diet and actually recommends using Regular (R) for meals to match the long lasting blood sugar rise from low carb meals. You could try using the IntraMuscular (IM) injection for a meal but you may still have issues. While it may accelerate the onset it may also wear out too fast and leave you with highs later on. Opinions vary on which insulin is fastest and how long they last. For the most part I think Apridra, Humalog and Novolog have pretty much similar onset, but some authorities think Apridra is has a much shorter duration.
I have done most of my shots into muscle because I don't have much fat and it's way to hard to aim for fat without going into skin. But I generally don't notice a difference in how fast it kicks in compared to when I do manage to go into fat.
My endo says absorption from muscles is less consistant, not necessarily faster, and that how much you exercise that muscle while it's absorbing increases absorption rate. Which I have noticed.