An endocrinologist's view on the practical use of insulin

The use of sliding-scale SC insulin for glycemic control in hospitalized patients with diabetes mellitus can produce clinically important fluctuations in blood glucose concentrations over time. Although the plasma concentration of insulin peaks after ∼2 hours, the stimulation of glucose utilization by insulin does not peak until 3 to 4 hours after SC administration. Thus, the repeated administration of sliding-scale SC insulin every 4 hours can create a large cumulative effect on glucose utilization and a precipitous decline in blood glucose concentration in a relatively short period of time. Even rapid-acting insulin analogues reach their peak effects on glucose utilization after ∼2 hours. At the University of Washington Medical Center in Seattle, Washington, a hospital-wide protocol has been developed for the use of IV insulin for hospitalized diabetic patients who are not eating or eating very little. An initial IV insulin dose is selected on the basis of the patient's insulin sensitivity, and subsequent doses are adjusted in response to changes in blood glucose values over time. The use of IV insulin reduces the likelihood that patients will develop hypoglycemia or hyperglycemia in both critical and noncritical care settings. Standardized methods, which are valuable for patient care and for educating clinicians about insulin use, have also been developed to transition patients to SC insulin.