Dr. Banting discovered insulin in 1921, not only rescuing the number of Type 1 diabetes, but also improving Type 2 patients' blood sugar control. Insulin preparations have evolved dramatically over the past 60 years, characterized by species source- from the primitive animal pancreas to the highly purified insulin preparations, and from the human insulin to human insulin analogue; and by time course of activity-from short-acting to intermediate-acting, long-acting, rapid-acting insulin analog and long-acting analog (just available in the year of 2000). The more kinds of insulin preparations, the more benefits for diabetes control are. Nevertheless more challenge for inexperienced clinicians as understanding the variety of insulin preparations and following clinical guidelines are necessary to lead patients into high quality glycemic control.