If you are reading this section, your doctor may have told you that you need insulin. If your blood glucose is not controlled by pills, or you have Type 1 diabetes, you will need insulin. It would be the only way to control your glucose.
Insulin is given by injection through a very fine needle. If insulin were swallowed, it would be digested (broken down) before being absorbed and it would have no action. The specific purpose of the injection is to get the insulin into the body intact, the only way your body can use it.
Nobody tells their doctor they like injections and want to be on insulin. Nevertheless, if a person needs insulin, they simply must be on it, injection or not. Rest assured that a lot of time and effort was spent developing syringes and needles for the specific purpose of giving insulin painlessly. These needles are like none you have ever felt in your life. They are incredibly fine and sharp, and coated with silicon to make them extremely smooth. Injecting insulin is not only painless, but you can barely feel it at all. Try the first few shots with an open mind. After the first few tries, you probably won't mind the injections at all.
Insulin was discovered in 1921. At first, short-acting soluble insulin was used. Then in 1936 it was discovered that the absorption of insulin could be delayed by mixing it with proteins or zinc. This produced a trend toward fewer daily injections, and ultimately a single injection daily with the insulins that were available. Ironically, we now know that multiple daily injections control glucose better and prevent many complications.
Insulins were originally derived from the pancreases of cows and pigs (giving us beef/pork insulin). Absorption of insulin was slowed with the addition of proteins such as Protamine (NPH insulin), and Zinc ("Lente" series). Over the years, the insulins have been purified. Human insulin was introduced in 1980 and its use has increased steadily. Human insulin is produced with gene technology. The human insulin gene is inserted into bacteria or yeast cells, which then churn out large quantities of insulin.