The invention relates to an injectable solution having a pH of 7, and including at least one type of basal insulin, the pI of which is between 5.8 and 8.5. The invention relates to a composition in the form of an injectable aqueous solution, the pH of which is between 6.0 and 8.0, including at least: a) one type of basal insulin, the isoelectric point (pI) of which is between 5.8 and 8.5 and b) a dextran substituted with radicals having carboxylate fillers and hydrophobic radicals of formula I or II, where R is -OH or is selected from the group consisting of the radicals o-(f-[A]-COOH), o-(g-[B]-k-[D])m, D comprising at least one alkyl chain comprising at least 8 carbon atoms, where R is -OH or a radical -(f-[A]-COOH)m, and R is selected from the group consisting of the radicals o-CH2NH-[E](-o- [F])t and o-C(O)NH-[E](- o-[F])t.
