Trehalose is a sugar consisting of two molecules of glucose. It is also known as mycose or tremalose. Some bacteria, fungi, plants and invertebrate animals synthesize it as a source of energy, and to survive freezing and lack of water. Organisms ranging from bacteria, yeast, fungi, insects, invertebrates, and lower and higher plants have enzymes that can make trehalose. In nature, trehalose can be found in plants, and microorganisms. In animals, trehalose is prevalent in shrimp, and also in insects, including grasshoppers, locusts, butterflies, and bees, in which trehalose serves as blood-sugar. Trehalose is then broken down into glucose by the catabolic enzyme trehalase for use.
Extracting trehalose was once a difficult and costly process, but around 2000, the Hayashibara company (Okayama, Japan) discovered an inexpensive extraction technology from starch. Trehalose has high water retention capabilities, and is used in food, cosmetics and as a drug. A procedure developed in 2017 and using trehalose allows sperm storage at room temperatures.

Trehalose is a disaccharide formed by a 1,1-glycosidic bond between two α-glucose units. Two other isomers are not found in nature. It is found in nature as a disaccharide and also as a monomer in some polymers.
Trehalose is rapidly broken down into glucose by the enzyme trehalase, which is present in the brush border of the intestinal mucosa of omnivores (including humans) and herbivores. It causes less of a spike in blood sugar than glucose. Trehalose has about 45% the sweetness of sucrose at concentrations above 22%, but when the concentration is reduced, its sweetness decreases more quickly than that of sucrose, so that a 2.3% solution tastes 6.5 times less sweet as the equivalent sugar solution.
It is commonly used in prepared frozen foods, like ice cream, because it lowers the freezing point of foods. The Cargill corporation promotes the use of its brand of trehalose, "Treha", as a substance that "enhances and intensifies certain flavors to bring out the best in your products."

Trehalose is an ingredient, along with hyaluronic acid, in an artificial tears product used to treat dry eye.

Formal Chemical Name (IUPAC)
(2R,3S,4S,5R,6R)-2-(Hydroxymethyl)-6-[(2R,3R,4S,5S,6R)-3,4, 5-trihydroxy-6-(hydroxymethyl)oxan-2-yl]oxyoxane-3,4,5-triol

References

https://en.wikipedia.org/wiki/Trehalose