High molecular weight poly(hydromethyl-co-dimethyl) siloxanes containing 0.6 and 3 mol-% of Si-H units are polar functionalized by the addition of various mono-, di- and oligosaccharides. Due to the hydrogen bond interaction between the carbohydrate moieties, the solution properties are strongly altered. Static and dynamic light scattering experiments as well as the dilute solution viscosities demonstrate the formation of intra- as well as intermolecular clustering. Despite the small number of carbohydrate groups, aggregation is very sensitive to the detailed chemical structure of the carbohydrate moiety. Disaccharides give rise to a stronger intramolecular clustering, while larger aggregates form in the case of monosaccharides. In addition, a surprising sensitivity of the macromolecular aggregation towards the stereochemistry of the carbohydrate residues is observed.