Oral Insulin Pills Could Replace Daily Injections

Diabetes patients have long dreamed of insulin in pill form. For over 100 years, scientists have tried to make it work. The challenge is the body itself. Enzymes in the digestive system break down insulin before it can act. In addition, the intestine struggles to absorb it into the bloodstream. As a result, many patients still rely on daily injections, which can affect quality of life.

Innovative Peptide Solution

A team at Kumamoto University, led by Associate Professor Shingo Ito, has developed a promising method. They use a cyclic peptide, called the DNP peptide, which can pass through the small intestine. This platform enables oral insulin delivery in a way that was previously impossible.
The researchers designed two strategies to improve intestinal absorption. First, the mixing method combines a modified “D-DNP-V peptide” with zinc-stabilized insulin hexamers. When tested on diabetes models, including chemical and genetic mice models, it quickly normalized blood sugar levels. Second, the conjugation method uses click chemistry to attach the DNP peptide directly to insulin. This approach lowered blood sugar just as effectively. Both methods confirm that the peptide actively helps insulin cross the intestine.

Lower Doses and Future Potential

Oral insulin usually requires very high doses, sometimes ten times that of injections. This new platform reduces the needed dose while achieving 33–41% bioavailability compared to subcutaneous injection. This makes oral insulin more practical for real-world use.
“Insulin injections remain a daily burden for many patients,” said Associate Professor Ito. “Our peptide platform offers a new oral delivery route and may apply to long-acting insulin and other biologics.”
The study, published in Molecular Pharmaceutics, is moving forward with tests in larger animal models and human-intestine-like systems. Researchers hope clinical applications may follow soon, giving patients a needle-free option.