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.
1 At this time scientists can not recommend an ideal amount of cocoa powder to eat. (1)  For people with type 2 diabetes, daily dark chocolate consumption of 20 grams per day (that was rich with polyphenols) helped increase the sensitivity to insulin. This is important for blood glucose control. Increasing insulin sensitivity may also help delay the onset of type 2 diabetes in people with pre-diabetes. (1)