The present invention relates to an insoluble composition comprising an acylated
protein selected from the group consisting of acylated
insulin, acylated
insulin analogs and acylated
proinsulin and preparations thereof. The formulations are suitable for parenteral or other delivery to a patient for prolonged control of blood glucose levels. More specifically, the present invention relates to compositions comprising an acylated
protein complexed with
zinc,
protamine and a phenolic compound such that the resulting microcrystals resemble the neutral
protamine zinc (NPH)
insulin crystalline form. Surprisingly; this acylated
protein composition has been found to have therapeutically superior subcutaneous release
pharmacokinetics, and longer and flatter glucose
kinetics than currently marketed NPH insulin formulations. Furthermore, the crystals of the present invention retain some of the advantageous properties of NPH crystals, namely being able to be easily resuspended and also mixed with soluble insulin.