The aggregation parameters of erythrocytes in hyperglycemic subjects with normal cholesterol and with hyper cholesterol were analyzed, and compared with control, by optical scattering under dynamic conditions. Aggregation of erythrocytes is determined by online erythrocyte aggregometer, based on sequential analysis of transmitted laser light intensity after passing through the erythrocyte suspension. The aggregation mechanism in terms of various parameters like process initiation time (PIT), process completion time (PCT), aggregation size index (ASI), effective number of cells (ENC), and effective cellular sedimentation duration (ECSD) is determined. The aggregation parameters thus obtained are used to describe quantitatively the dynamic nature of aggregation process under gravitational sedimentation. The present data show that, in diabetes mellitus with normal cholesterol, the aggregation of erythrocytes is increased and in diabetes with hyper cholesterol, the aggregation is further increased significantly. These changes may significantly affect the flow properties of erythrocytes in microcirculation in diabetes mellitus with hyper cholesterol.