Aim:The rheological properties of erythrocytes are impaired in diabetes mellitus, especially because of changes in their membrane lipid composition.The aim of this study was to determine and examine the relationship between red blood cell (RBC) membrane and serum lipid composition in type II diabetes subjects with and without nephropathy.Methods:Trinidadian subjects aged 18–65 years were recruited for the study regardless of gender and ethnicity. Fasting blood samples were collected from 60 subjects of whom 20 were healthy individuals, 20 had type II diabetes without complications, and 20 were type II diabetics with nephropathy. Weight, height, waist/hip ratio, and blood pressure were recorded. All the blood samples were analysed to determine the serum lipid concentration, membrane lipid composition and plasma glucose concentration.Results:The body mass index and the systolic blood pressure of the diabetics (28.17 ± 4.98 kg/m2, 153.21 ± 22.10 mmHg) and those with nephropathy (25.87 ± 4.68, 158.60 ± 22.49 mmHg) were higher when compared with controls (24.67 ± 5.18, 119.15 ± 13.03 mmHg). The diabetic (175.89 ± 102.73 μg/mgprotein) and diabetic nephropathy (358.80 ± 262.66) subjects showed significantly higher levels of RBC membrane cholesterol compared with controls (132.27 ± 66.47). The membrane phospholipids, protein and Na+/K+ATPase concentrations were altered in diabetics and diabetic nephropathy patients when compared with controls. The trends of increased serum cholesterol and decreased high-density lipoprotein in diabetics and diabetic nephropathy patients were noted as compared with controls but they are not significant as expected. The low-density lipoprotein cholesterol was significantly higher in diabetics when compared with diabetic nephropathy and control subjects.Conclusions:Our data suggest that there is a relationship between RBC membrane and serum lipid composition in subjects with type II diabetes with and without nephropathy. This relationship shows that diet and lifestyle plays a significant role in the alterations of the lipids both in serum and RBC membrane. The membrane and serum lipid composition may be used as possible indicators for type II diabetic patients with and without nephropathy to control their diet in the beginning stages to prevent them from further complications.