You draw insulin out of a small bottle into a needle at a dosage recommended by your doctor. After filling the needle with the recommended dosage you inject yourself in either the leg, arm, stomach, hip or buttocks. (Taken from: Learning to Live Well with Diabetes).
The shots can be much more of a hassle. You have to draw the insulin into the needle and inject it into yourself two to five times a day. When you take shots there are a few different types of insulin that you can take, such as Humulin NPH (long lasting- works over a six-hour period and slowly peaks within three hours), Humulin Regular (fast acting- works over a three hour period and peaks within a half hour), and Humulin Humalog (fast acting- starts working right away). If you are taking anything other than Humalog you have to wait thirty minutes after taking the shot to eat.
The insulin pump, on the other hand, can hold up to 300 units of insulin. It is battery powered and a little smaller than a deck of cards. You program how much insulin to be pumped into your body each independent hour. The pump has tubing running from itself to the injection site. The site is basically an adhesive bandage. On one side of the bandage there is a port to plug the tubing into and on the other side is a needle, which is inserted under your skin. (Taken from: Learning to Live Well with Diabetes).
Because you are able to program the amount of insulin the pump releases each hour the pump acts more like your pancreas would. Instead of just receiving insulin in large doses a couple times a day, you get it in very small doses all day long. It keeps your blood sugar more stable. When you are going to eat you have to count the carbohydrates in your meal, or guess at how many you think there are, and give yourself the appropriate amount of insulin (this is called bolusing). With the pump you only need to change the site every three days and the insulin cartridge every two to four days.