Glycolaldehyde (IUPAC name hydroxyacetaldehyde) is the simplest molecule that is both an alcohol and an aldehyde. It shares with monosaccharides (“sugars”) a formula (H2CO)n so that it can be considered formally to be a polymer of formaldehyde H2CO and to be a carbohydrate. It is an intermediate in the formose reaction. Monosaccharides have n ≥ 3, so that glycolaldehyde is a “pre-sugar” rather than a sugar. Glycolaldehyde has been identified in the interstellar medium.
Hollis et al. (2000) identified glycolaldehyde for the first time in the interstellar medium, toward the Galactic center.