Proteins are necessary for tissue repair and for the construction of new tissue. Every cell needs protein to maintain its life. Protein is also the primary substance used to replace worn out or dead cells. Your muscles, hair, nails, skin, and eyes are made of protein.
Taking supplemental chromium has been shown repeatedly to improve insulin sensitivity and glucose tolerance, even to the point of reversing type II diabetes in many people (1). Thus, as my old clinical nutrition professor pointed out, apparently a chromium deficiency can actually lead to type II diabetes.
Bonus Training Tip. The focus of this article is nutritional strategies to improve insulin sensitivity, but there's also a training tip that's worth sharing. I don't know that it's been proven through research, but I believe that high volume, glycogen-depleting training can, over time, improve insulin sensitivity. Let me explain.