Taste receptors in the intestines

It’s now clear that taste receptors do not reside merely in the mouth. They’ve been found in the lungs, in the testes, and certainly in the gastrointestinal tract. Richard Young and his colleagues from the University of Adelaide show that taste receptors in our guts play an important role not only in glucose regulation, but also in management of type 2 diabetes.

The researchers confirmed that intestinal sweet taste receptors (STRs) are expressed in different amounts, depending on the amount of glucose within the intestines. They then compared STR expression in fourteen healthy subjects and thirteen type 2 diabetes patients.

Expression of the STRs was the same in both groups of people during fasting, but differed between the two groups when they were challenged with glucose. When the participants were made hyperglycemic (having an abnormally high concentration of glucose in the blood) the expression of the STRs dramatically decreased in normal people but increased in diabetes patients. These same type 2 patients also had increased glucose absorption compared to healthy controls.

Young explains these results:

When sweet taste receptors in the intestine detect glucose, they trigger a response that may regulate the way glucose is absorbed by the intestine. Our studies show that in diabetes patients, the glucose is absorbed more rapidly and in greater quantities than in healthy adults. 

This shows that diabetes is not just a disorder of the pancreas and of insulin -- the gut plays a bigger role than researchers have previously considered. This is because the body's own management of glucose uptake may rely on the actions of sweet taste receptors, and these appear to be abnormally controlled in people with type 2 diabetes.

It certainly makes sense that the same receptors would be used not only to detect glucose but also to regulate glucose uptake.

Young RL, Chia B, Isaacs NJ, Ma J, Khoo J, Wu T, Horowitz M, & Rayner CK (2013). Disordered control of intestinal sweet taste receptor expression and glucose absorption in type 2 diabetes. Diabetes PMID: 23761104.