Relevance of measuring red blood cell disaggregability in insulin-dependent diabetic patients

Abstract

A viscometric study of blood from insulin-treated diabetic patients is carried out. Patients are divided into three major groups—group I: without or with minimal retinopathy and recent diabetes ( n = 37), group II: without or with minimal retinopathy and at least 20 years of diabetes duration ( n = 35), group III: with severe retinopathy ( n = 27). Each group is also subdivided according to the glycosylated hemoglobin (HbA 1c) level, used to assess long-term glycemic control. Finally, the rheological parameters of six groups are compared: three of which have a HbA 1c level less than 7.5% [I 1 ( n = 15), II 1 ( n = 9), III 1 ( n = 9)] and three others have a HbA 1c level more than 7.5% [I 2 ( n = 22), II 2 ( n = 26), III 2 ( n = 18)]. The most important result concerns the thixotropy index ξ t , which reflects the dynamic property of red blood cell (RBC) disaggregability under shear. Strong correlations between this parameter and HbA 1c level are found for groups I ( r = −0.53, p < 0.001) and II ( r = −0.68, p < 0.001), providing evidence of a RBC disaggregability disorder for a poor glycemic control of diabetes. In contrast, such a correlation is not pointed out for the group II. As the value for ξ t is not statistically different for groups II 1 and II 2 and is close to the normal value in both groups, the existence of a rheological protection against the retinopathy could be involved. If such a hypothesis was verified, the systematic measurement of the thixotropy index for insulin-dependent diabetic patients would allow the patients susceptible to retinopathy to be detected and, therefore, the insulin therapy to be optimized.