A patient with type 2 diabetes is switched from neutral protamine Hagedorn (NPH) insulin to insulin glargine for basal coverage. The property of glargine that makes it truly 'peakless' is:

• A Binding to albumin at the injection site, creating a slowly released reservoir
• B High molecular weight preventing rapid vascular absorption
• C Formation of insulin hexamers that slowly dissociate to monomers for absorption
• D Precipitation at physiological pH forming a depot that dissolves slowly and predictably ✓

Explanation

Insulin glargine has two extra arginine residues at the C-terminus of the B chain and an asparagine→glycine substitution at A21, shifting its isoelectric point to 6.7. When injected subcutaneously at tissue pH 7.4, it precipitates (is insoluble) forming microcrystalline aggregates. These slowly dissolve and release insulin monomers over 20–24 hours, creating a flat, peakless absorption profile. NPH uses protamine to delay absorption but still has a peak at 4–8 hours.

Reference: KD Tripathi, Essentials of Medical Pharmacology, 8th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.