This work presents data which indicates the presence of Amadori product derived from Maillard reaction in aminophospholipids. The presence of 5-HMF, a stable derivative of acid-treated Amadori product, in the phospholipidic fraction from cell membranes was established by HPLC-UV and subsequent GC/MS analysis. The assay for 5-HMF in rat liver phospholipid revealed the presence of this molecule in membrane phospholipids of euglycemic rats, and showed increased glycation levels in membrane phospholipids from streptozotocin-induced diabetic rats (p < 0.001). This gives a new insight to cell membrane physiology and physiopathology.