Introduction Type 1 diabetes and many cases of type 2 diabetes are treated with insulin injections. For decades, these injections have been the only way to deliver insulin. You might wonder, why hasn’t an easier way to give insulin been developed? The truth is, for more than 80 years, people have been trying to develop a form of insulin you can swallow. Pharmaceutical companies, government agencies, and universities have done extensive research in hopes of developing this “holy grail” of diabetes treatment. Where do we stand in the process?

Why oral insulin? If you have any type of diabetes, keeping your blood sugar levels within your target range is vital. Not doing so raises your risk of serious health problems such as blindness, heart disease, kidney disease, and nerve damage. To keep your blood sugar levels in a safe range, you have to follow your diabetes treatment plan. For many people with diabetes, this involves insulin injections. These injections can be inconvenient, they require training to self-administer, and they may need to be given several times per day. And, of course, they involve needles, which many people don’t like. For all of these reasons, many people don’t follow their diabetes treatment plan, which can lead to severe complications. So, the idea that you could get your dose of insulin by simply swallowing a pill appeals to many people. Doctors believe that the ease of using a pill could make more people willing to start and maintain a successful insulin therapy routine. That could lead to better control of their diabetes.

How oral insulin would work With injectable insulin, you use a needle to inject the insulin into the fatty tissue beneath your skin. From there, the insulin travels to your bloodstream. It goes into general circulation throughout your body and then travels to your liver. Oral insulin, on the other hand, would move through your digestive system. It would be absorbed into your bloodstream through your intestines. From your intestines, it would move into your portal vein, a blood vessel that connects to your liver. Then the insulin would move directly into your liver, where glucose (blood sugar) is stored. The process with oral insulin would more closely mimic the movement of natural insulin in your body than injectable insulin does. Moving insulin more quickly into your liver could help your body absorb and use glucose better. This could mean the insulin works faster. It could also mean a reduced risk of excess insulin in your blood, which could lead to a decreased risk of hypoglycemia (low blood sugar).

Why we don’t have oral insulin yet We haven’t developed a type of oral insulin that can make it through the digestive system unharmed. The acids in your stomach break down oral insulin before it can get to your liver. That means it’s not effective by the time it reaches your liver. Further, your body has trouble absorbing insulin from your intestines. The mucus layer in your intestines is thick, and studies have shown that only low levels of insulin pass through this lining and into your bloodstream. As a result, some researchers believe that high doses of insulin would be needed to be effective in managing diabetes. Many clinical trials have been done on oral insulin, but no form of the treatment has made it through the trials successfully. The good news is, none of these trials has shown major health risks from oral insulin as compared to injectable insulin. However, researchers are concerned that oral insulin could raise the risk of certain types of cancer. This is because large amounts of insulin would be needed to make it through the digestive system. Insulin is a growth-promoting substance, and large amounts of it could promote the growth of cancer cells. The bottom line, though, is that there’s no established link between oral insulin and cancer.

Current and future options While researchers continue to strive for a pill form of insulin, another form is now available. Afrezza inhalation powder was approved by the Food and Drug Administration in 2014. Using an inhaler, you breathe in this drug at the start of a meal to help control spikes in blood sugar after your meal. The drug is absorbed into your bloodstream through the walls of your lungs. This method is not quite as desirable as a pill form, as it doesn’t go into your liver as quickly. You can use Afrezza if you have type 1 or type 2 diabetes. However, with type 1, you must use injectable insulin as well. Clinical studies are ongoing for other oral forms of insulin. For instance, a buccal spray is being studied. This drug would be sprayed into your mouth and absorbed into your bloodstream through the mucus membrane of your cheek.