OBJECTIVE -To measure with ultrasound the increased erythrocyte aggregation (EA) kinetics and adhesion energy between erythrocytes in patients with type 2 diabetes and poor metabolic control.RESEARCH DESIGN AND METHODS -Blood samples were analyzed in a Couette rheometer at 32 MHz following shear rate reductions from 500 s Ϫ1 to residual shears of 0 (stasis), 1, 2, 10, 50, 100, and 200 s Ϫ1 . The increase in EA was determined with the integrated backscatter coefficient as a function of time and shear rate.RESULTS -The time required to form aggregates was shorter in diabetic patients at shear rates below 200 s Ϫ1 (P Ͻ 0.01). Erythrocytes formed larger aggregates in diabetic patients than in control subjects (P Ͻ 0.05 at 2 to 100 s Ϫ1 ).CONCLUSIONS -Ultrasound can potentially noninvasively demonstrate, in vivo and in situ, the impact of local abnormal EA on arteriovenous flow disorders in diabetes. Diabetes Care 31:1400-1402, 2008F low disorders in diabetes often lead to severe outcomes in various organs and tissues; abnormal rheology of erythrocytes (RBC) likely impairs macroand microcirculatory blood flow, tissue oxygenation, and vascular tone regulation in affected patients (1-3). Diabetic retinopathy is attributed to microvascular flow disorders and enhanced RBC aggregation (4). Erythrocyte aggregation (EA) and plasma viscosity are also predictive of diabetic foot syndrome deterioration (5). EA is a reversible phenomenon responsible for increased blood viscosity at low shear rates. RBC hyperaggregation can also promote flow stasis and thrombosis in macrocirculation. This study proposes an ultrasound method that has the potential to noninvasively detect early rheological disorders in situ in blood vessels. The method is based on backscattering of ultrasound by blood; it measures the extent of EA and its shear rate dependency. RESEARCH DESIGN AND METHODS PopulationsRecruited individuals were nonsmoking males. They completed a questionnaire on current medications and medical history. BMI and blood pressure were measured. Nine patients with type 2 diabetes and eight healthy control subjects gave informed consent to the approved protocol. Patients with poor metabolic control were intentionally chosen. Lipid profile and inflammatory proteins (fibrinogen, Von Clauss method; haptoglobin and immunoglobin G, immunonephelometric method; and C-reactive protein, latex agglutination technique) were determined for each participant.Six patients were on oral antidiabetic and aspirin medications, three were on insulin, five were on cholesterol-lowering therapy, and four were treated for hypertension. Those on insulin had a history of coronary artery disease, and two of them had suffered from myocardial infarction. Distal angiopathy or cutaneous trophic disorders were not present. Mean Ϯ SD age of patients was 58.3 Ϯ 8.8 years (range 41-70). Healthy subjects were age matched (51.1 Ϯ 8.7 years [range 41-64]), did not take regular medications, and had no history of cardiovascular disease. None had lipid disorders or hypertension. C...

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