Analysis of membrane fluidity alterations and lipid disorders in type I diabetic children and adolescents.

The degree of random orientation of excited diphenylhexatriene molecules in isolated erythrocyte membrane ghosts was investigated in order to determine the possible effect of lipid disorders on membrane structure in children suffering from type I diabetes mellitus with and without diabetic retinopathic lesions. A decrease of cholesterol in the antiatherogenic fraction HDL (1.17 +/- 0.06 in retinopathy vs 1.24 +/- 0.065 in controls) and its increase in atherogenic LDL fraction (3.88 +/- 0.23 vs 2.63 +/- 0.26) as well as developing erythrocyte membrane rigidization in diabetes and retinopathy (0.193 +/- 0.008 and 0.204 +/- 0.014 vs 0.161 +/- 0.008 in controls) were observed. Considerable fluctuations in plasma and membrane cholesterol:phospholipid ratio were most pronounced in subjects exhibiting diabetic background retinopathy. The content of membrane cholesterol compared significantly with both membrane fluidity (r = 0.677), cholesterol of LDL (r = 0.667) and cholesterol:phospholipid ratio in HDL (r = 0.693) which suggests a destructive effect of lipid disorders on cell membrane structure in diabetics.