Insulin is an often life-saving drug that has allowed millions of diabetic Americans to live relatively happy and normal lives. However, administering insulin to the body can be an inconvenience, as insulin has traditionally been administered through various injector devices. Because of the hassle associated with current insulin delivery systems, much attention and research has been directed at developing an ingestible insulin product.

However, certain chemical and biological factors have posed substantial barriers to progress in this area. This article will explore these factors, as well as reviewing the most current science and research available on the topic. Alternative ingestible anti-diabetic drugs will also be canvased as potentially effective and convenient treatments for some diabetics.

The Importance of Insulin

In non-diabetic individuals, insulin is a naturally occurring hormone produced in the pancreas. Once released into the body, this hormone plays the critical role of regulating levels of glucose (a form of sugar) in the blood. This goal is accomplished by causing glucose to be imported from the bloodstream into the cells of the body, where it can be used as energy. To regulate glucose effectively, insulin must be released in careful balance with the intake of carbohydrates and their release into the bloodstream; thus, insulin spikes naturally tend to correspond to meals and other factors.

In people with diabetes, however, the body either does not produce enough, or any, insulin (type 1 diabetes) or does not properly respond to insulin (type 2 diabetes). Whether due to a lack of insulin production or an insensitivity to circulating insulin, the failure of a diabetic’s cells to import sugar from the blood causes it to accumulate there. The resultant excess of blood sugar can cause damage to sensitive organs and tissues over time. Thankfully, synthetic insulin products have been available for decades, and have allowed a means of controlling blood sugar levels to those whose bodies could not ordinarily do so.

How is Insulin Currently Administered?

There are four main methods currently in use to deliver insulin to the body. Each varies in popularity and comes with its own set of pros and cons, and none should be selected without the consultation and advice of a physician.

Syringes or pens

Injecting insulin via pens and syringes are two of the most widely used options. Syringes represent perhaps the most basic option available and are generally the least convenient but most cost-effective. They consist of a small barrel, a plunger, and a needle. Adjusting dosages can be difficult, and carrying around a supply of syringes and the vials of insulin required to load them can pose a clear burden. However, their relative cheapness can make the inconvenience worth it, especially for those who take insulin less frequently.

Insulin pens, so named for their resemblance to the writing utensil, are meant to provide more convenience than a standard syringe. They contain a replaceable cartridge of insulin which can be stored and swapped without fussing with insulin vials. The pens have a dial on the side to adjust the dosage and a needle to inject the insulin. Many view pens as a significant improvement in the overall experience of administering insulin, though they too have their drawbacks. Namely, their price can make them unattractive, and they still need to be lugged around with their user.

Insulin Pumps

An insulin pump is another method of delivering insulin via injection. This small device is worn on the body and is always connected to the bloodstream through a small catheter inserted under the skin. The pump delivers a continuous low supply of insulin into the bloodstream, the dosage of which can be adjusted easily as necessary. For instance, some individuals may be able to self-administer additional insulin through their pump when they experience a spike in blood sugar, such as those that often occur following a meal.

Pumps represent an improvement in convenience over syringes and pens. They remove the need for individuals to constantly poke themselves throughout the day, or to remember to administer their doses at the proper time. They are not without flaws, though, as constantly wearing an electronic device brings the chores of keeping it charged, loaded, and sanitary.

Jet Injectors

Jet injectors are devices that deliver insulin through the skin using a high-pressure stream of air or gas to pierce the skin, rather than a needle. Though similar to a needle in administering insulin through an opening in the skin, they are designed to be a needle-free alternative to traditional insulin injections.

These devices are often able to deliver insulin more comfortably and consistently than needles, while also offering greater control over blood sugar levels than the inhaler. Patients with an anxiety or aversion toward needles may also find these to be a more comforting option. However, just like the inhaler, jet injectors are also not widely available and are not suitable for everyone.

Inhalers

The insulin inhaler is among the newer and more innovative categories on this list. Inhalers are devices that deliver insulin in the form of a dry powder through the mouth and into the lungs, where it is absorbed quickly into the bloodstream. These can serve as an alternative to injectable pre-meal insulin and are generally administered immediately before a meal.

This method of delivering insulin is meant to be a more convenient and less painful way of managing diabetes than those that require users to break the skin. With that said, insulin inhalers are not widely available, are still in development, and may not be able to provide the same level of glucose control as injections or pumps.

The Positive Potential of Pills

Each of the currently available methods for delivering insulin has its drawbacks and lacks the convenience that many diabetics seek in administering insulin. An orally administered insulin pill would solve many of these issues, hence the interest and research within the scientific community to bring it into existence.

The primary benefit of an insulin pill would be the convenience it would afford patients. The freedom to take insulin without worrying about needles or the associated pain and discomfort would be a tremendous benefit to many diabetics. This convenience could also result in better diabetes management by reducing treatment avoidance or resistance by some patients who object to the hassle of needles.

Additionally, an insulin pill could revolutionize access to this life-saving medication. Pills are more easily transported and stored than fragile syringes and vials, potentially reducing the logistical costs of delivering these products to remote areas. This could help finally break the pattern of extraordinarily high insulin prices that has characterized the American struggle against diabetes and allow those who lack the resources to purchase traditional insulin or insulin delivery devices to access proper care.

Obstacles to Ingesting Insulin

Though the potential benefits of an insulin pill are many, significant challenges currently hinder its development. The difficulty largely stems from the trouble insulin has making it through our digestive system, to the bloodstream, intact. The acids and enzymes in our stomachs break down oral insulin before it can reach the bloodstream, rendering it ineffective by the time it arrives.

Even if insulin could be protected from the harsh environment of the GI tract, studies have shown that the body has trouble absorbing insulin through the intestines[1]. The mucus layer in the intestines is thick, only allowing low levels of insulin to pass through into the bloodstream. As a result, some researchers believe that higher doses of oral insulin per administration would be needed to effectively manage diabetes as compared to injectable insulin.

Although many clinical trials have been conducted on oral insulin, unfortunately, no form of the treatment has made it through successfully. However, the goal of some promising current research is to find a way to protect insulin from the stomach’s acidity and deliver the insulin to the small intestine intact. Scientists and pharmaceutical companies are researching various methods to protect the insulin, such as applying a protective coating that dissolves in the small intestine, using nano-particles to deliver insulin directly to the bloodstream, using specially designed particles and other advanced technology[2]. Other researchers are also investigating the use of enzymes that can break down insulin in the stomach and small intestine, making it more bioavailable[3]. Though many of these studies have yielded hopeful results, none yet have led to conclusive determinations as to the viability of these methods. Regardless, they generally give cause for optimism for the future of this line of research.

Alternative Oral Anti-Diabetic Medications

Although insulin pills do not currently exist, other pill-based options can contribute to a diabetes treatment plan for certain individuals. These pills include:

  • Oral hypoglycemic agents (OHAs): these pills lower blood sugar levels by stimulating the pancreas to produce more insulin or by helping the body use insulin more effectively.
  • Alpha-glucose inhibitors: these pills slow down the absorption of carbohydrates from the gut, which help lower blood sugar levels after meals.
  • Bile acid sequestrants: these pills lower cholesterol levels by binding to bile acids in the gut and preventing them from being reabsorbed into the bloodstream.

It is important to remember that these pills are not insulin, nor are they an insulin replacement, but they can be used in combination with insulin therapy or as an alternative for people with type 2 diabetes. As always it is important to discuss with your healthcare team before making any changes to your diabetes treatment plan.

Conclusion

Diabetics have many reasons to be grateful for insulin. This substance has extended and improved the quality of countless lives globally since its discovery mere decades ago. Unfortunately, the current technology for its administration leave diabetics with may legitimate gripes about taking insulin. The inconvenience and cost associated with even the most modern of medical devices for insulin delivery render them an unappealing or inaccessible option for many who would much prefer a simple pill.

Fortunately, scientific advances continue to bring us closer to overcoming the hard challenges that have blocked such progress until now. Though it would not be possible to predict if or when such efforts will successfully culminate in a stable, effective, and economical insulin pill, diabetics can feel optimistic about the future of such treatments.

[1] https://journals.sagepub.com/doi/pdf/10.1177/193229680900300323

[2] dst.sagepub.com/content/3/3/562.full.pdf+html

[3] https://www.mdpi.com/2079-7737/9/9/252