Intensive insulin therapy is composed of an entire therapeutic program of diabetes management. One component of that program is a multiple-component insulin regimen. There are several important pharmacokinetic issues that must be appreciated when prescribing insulin. These include differences in absorption characteristics between animal and human insulin, variations in intraindividual insulin absorption, the influence of injection sites on insulin absorption, and lag time. Only physiologic insulin regimens should be used in patients with type I diabetes, and there are advantages and disadvantages to the various available options. There are theoretic reasons why CSII may be better for many patients. Finally, the nurse specialist/educator who is initiating the insulin therapy should be familiar with the general guidelines for the various insulin regimens in addition to implementing appropriate diabetes algorithms.