Many physicians will manage the care of hospitalized patients with diabetes mellitus who require parenteral nutrition or enteral tube feeding. The nutritional assessment, indications for nutrition support, estimate of nutritional needs, and biochemical monitoring guidelines for critically ill patients with diabetes are similar to those for nondiabetic patients. In general, a weight loss of up to 10% of body weight is well tolerated and, in the absence of severe stress, the provision of dextrose-containing crystalloid solutions and electrolytes is adequate for as long as 7 to 10 days. Studies that demonstrate a beneficial influence of nutrition support on clinical outcome administered nutrition for a minimum of 1 week. No data have established that support for a briefer duration is of clinical benefit. An important goal in the care of the hospitalized patient with diabetes is to avoid the extremes of hypoglycemia and hyperglycemia. Herein we provide our approach to achieving glucose control in stressed hospitalized patients with diabetes mellitus who are receiving parenteral and enteral nutrition. Although evidence is increasing that hyperglycemia impairs immune function, well-designed prospective randomized trials are needed to determine the risks, costs, and benefits of achieving glucose control and of providing nutrition support to hospitalized patients with diabetes mellitus.