• Rapid-acting: Usually taken before a meal to cover the blood glucose elevation from eating. This type of insulin is used with longer-acting insulin.
• Short-acting: Usually taken about 30 minutes before a meal to cover the blood glucose elevation from eating. This type of insulin is used with longer-acting insulin.
• Intermediate-acting: Covers the blood glucose elevations when rapid-acting insulins stop working. This type of insulin is often combined with rapid- or short-acting insulin and is usually taken twice a day.
• Long-acting: This type of insulin is often combined, when needed, with rapid- or short-acting insulin. It lowers blood glucose levels when rapid-acting insulins stop working. It is taken once or twice a day.

A Guide on Insulin Types for People with Diabetes