Some bacteria, fungi, plants and invertebrate animals synthesize it as a source of energy, and to survive freezing and lack of water.

[8] Trehalose is a nonreducing sugar formed from two glucose units joined by a 1–1 alpha bond, giving it the name α-D-gluco­pyranosyl-(1→1)-α-D-gluco­pyranoside.

The bonding keeps nonreducing sugars in closed-ring form, such that the aldehyde or ketone end groups do not bind to the lysine or arginine residues of proteins (a process called glycation).

[10] Organisms ranging from bacteria, yeast, fungi, insects, invertebrates, and lower and higher plants have enzymes that can make trehalose.

[citation needed] The concentrations of both trehalose and glucose in the insect hemolymph are tightly controlled by multiple enzymes and hormones, including trehalase, insulin-like peptides (ILPs and DILPs), adipokinetic hormone (AKH), leucokinin (LK), octopamine and other mediators, thereby maintaining carbohydrate homeostasis by endocrine and metabolic feedback mechanisms.

[11][19] In bacterial cell wall, trehalose has a structural role in adaptive responses to stress such as osmotic differences and extreme temperature.

[citation needed] Trehalose has also been reported for anti-bacterial, anti-biofilm, and anti-inflammatory (in vitro and in vivo) activities, upon its esterification with fatty acids of varying chain lengths.

[22] 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.

[32] Trehalase in humans is found only in specific location such as the intestinal mucosa, renal brush-border, liver and blood.

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

[38] In 2021, the FDA accepted an Investigational New Drug (IND) application and granted fast track status for an injectable form of trehalose (SLS-005) as a potential treatment for spinocerebellar ataxia type 3 (SCA3).

[43] In 2017, research was published showing that trehalose induces autophagy by activating TFEB,[44] a protein that acts as a master regulator of the autophagy-lysosome pathway.