Which of the following is required for proper effects of Insulin?

In association with insulin, chromium promotes the utilization of glucose Chromium is a component of a protein namely chromodulin which facilitates the binding of insulin to cell receptor sites Chromium It is an essential nutrient for the maintenance of normal glucose tolerance Its deficiency causes insulin resistance. Chromium administration has also been shown in several studies to lower glucose and insulin levels in patients with type 2 diabetes. It has been classified as not essential for mammals. (Cr (III) or Cr3+). Ref: Guyton 12th Ed.