It is estimated that about 6 percent of the world's population suffers from type 2 diabetes. Labelled a global health epidemic by the World Health Organization, rates of the disease increased dramatically from about 30 million cases in 1985 to around 390 million by 2015. A new study has now found a previously undiscovered mechanism that raises the possibility of type 2 diabetes being transmitted in a way similar to infectious diseases such as Bovine Spongiform Encephalopathy (mad cow disease).

Unlike type 1 diabetes, type 2 is known to develop with age and is generally thought to occur as a result of lack of exercise and obesity. The dramatic increase in the disease all across the world over the past 50 years is still not clearly understood by scientists.

A team of researchers at the University of Texas has been focusing on a number of abnormal protein deposits found in over 90 percent of patients with type 2 diabetes. It was identified that this large majority of patients suffering from the disease had aggregates of a misfolded form of the protein islet amyloid polypeptide (IAPP).

Small amounts of misfolded IAAP proteins were then injected into mice and the researchers found that this induced the formation of protein deposits in the animal's pancreas. Most striking was the observation that within weeks of receiving the misfolded IAAP aggregates the mice displayed several symptoms associated with type 2 diabetes, from elevated blood glucose levels to a loss of pancreatic beta cells.

The research is yet to identify how these misfolded IAAP proteins could bring on a case of type 2 diabetes but the scientists hypothethize that once a large enough volume of these proteins aggregate in the pancreas they may be capable of damaging and killing the body's beta cells that secrete insulin.

A large protein aggregate (green) forms in a pancreatic islet (red) from a transgenic mouse injected with extract containing misfolded IAPP Mukherjee et al., 2017

The enormous implication of the research means that type 2 diabetes could be similar to other diseases that are transmitted and caused by these types of misfolded protein aggregates.

Known as prion diseases, these illnesses are unlike other infectious diseases that are spread by viruses or bacteria. A prion is composed of misfolded proteins and can act as an infectious agent that enters a healthy organism and propagates that misfolded state across other proteins.

The most infamous prion disease of recent times is Bovine Spongiform Encephalopathy, or what is more colloquially known as "mad cow disease". The disease originates in cattle and is spread to humans through eating tainted meat that contains specific misfolded proteins, or prions.

In the case of this new research the scientists are quick to assuage any hyperbolic fears. This is not proof that type 2 diabetes is something we can simply "catch", but the team is keen to research the potential of it being transmissible in a variety of ways, from blood transfusions to eating meat containing high levels of misfolded IAAP proteins.

"Until now, this concept has not been considered," says one of the researchers on the project Claudio Soto. "Our data therefore opens up an entirely new area of research with profound implications for public health."

Separate to the more extreme interpretation of type 2 diabetes as an infectious disease, a more pragmatic outcome from this discovery is an insight into how the illness could progress in an individual. While we know that exercise and a healthy diet can hold back, and in some cases reverse, the onset of type 2 diabetes, this research offers a key insight into what may fundamentally trigger the condition.

The research was published in The Journal of Experimental Medicine.

Source: The University of Texas