For more than 80 years, pharmaceutical companies, government agencies, and universities have researched in hopes of developing an oral form of insulin. It is something of a holy grail of medical innovation: an oral form of insulin would prevent the unpleasantness of insulin injections, make insulin therapy less complicated, and, most importantly, hopefully increase the rate at which insulin users comply with their insulin therapy schedule. Unfortunately, no forms of oral insulin are currently available in the United States.
Nevertheless, the question seems to be “when” and not “if” oral insulin will be ready for the market.
How Oral Insulin Works
Keeping your blood sugar levels within your target range is vital to anyone with diabetes. Failure to do so increases your chances of developing diabetes complications, including blindness, heart disease, kidney disease, and nerve damage. Unfortunately, many people with type 2 diabetes find it difficult to maintain their blood sugar levels for one reason or another.
The idea that you can simply swallow a pill to control your blood sugar levels appeals to many people. Doctors believe that the ease of taking a pill, when compared to the complicated process of preparing an insulin injection, would result in more people willing to start and maintain a successful insulin therapy routine.
Oral insulin would enter your bloodstream through absorption in your intestines. Once it entered your bloodstream it would move immediately to your liver and help your body better absorb and use glucose (blood sugar). Because it would ideally mimic the natural process of insulin so closely, oral insulin may reduce the risk of excess insulin in your blood, thus leading to a decreased risk of hypoglycemia.
Why Oral Insulin Doesn’t Work
The main reason that developing an oral insulin therapy hasn’t been so easy is due to the inability of potential oral insulin delivery systems to make it through your digestive system unharmed. Your digestive system is designed to break proteins down into amino acids, in order to prevent the absorption of dangerous forms of protein. Part of this process includes maintaining a very low pH level in your stomach. This low pH level destroys, or breaks down, all peptides. Oral insulin is a type of protein that contains complex peptide bonds. Therefore, the acids in your stomach break down oral insulin before it can get to the liver.
Another risk associated with oral insulin involves your ability to absorb it from your gut. Due to the fact that the mucus layer in your intestines is very thick and does not flow easily, the possibility of insulin passing through this lining and into your blood is believed to be relatively low, according to a research review published in the May 2009 issue of The Journal of Diabetes Science and Technology. Only a small amount of insulin effectively reached the liver in the studies used in this May 2009 review.
In clinical trials, there have been no significant health risks associated with oral insulin compared to regularly administered insulin. However, because large amounts of insulin are required to make it through the digestive system, and because insulin is a growth-promoting substance, researchers are concerned that oral insulin could raise the risk of certain types of cancer.
What The Future Holds
Laboratories worldwide are currently in various stages of testing oral forms of insulin, including, among others, Novo Nordisk, Eli Lilly, Pfizer, Sanofi-Aventis, the Israeli company Oramed, and the largest pharmaceutical company in all of Asia, India’s Biocon.
Two companies, Mannkind and Generex have developed inhaled insulin sprays, and have presented them to the U.S. Food & Drug Administration (FDA). The FDA has yet to approve either.