Abstract. Background and Aims. Diabetic microangiopathy is a specific vascular complication of diabetes mellitus type 2, which matters to patients' mortality and individual prognosis. Therefore, an important problem is the development of non-invasive methods for the diagnosis of diabetic microangiopathy, such as laser Doppler flowmetry (LDF). This work aimed to analyze some correlations between LDF spectral indicators and the level of glycated hemoglobin in patients with chronic kidney disease and type 2 diabetes.
Method. The study included 55 patients (26 men and 29 women) with type 2 diabetes mellitus. The age of patients was 58-77 years. The duration of diabetes was more than 5 years. All patients had chronic kidney disease (stage C3-C4) caused by diabetic nephropathy. For Laser Doppler flowmetry we used the “LDF 100C” system (“Biopac Instruments”, USA). Each patient had a 10-minute LDF registration on the skin of the rear of the foot. Using the special software, we have assessed slow, respiratory and pulse flux motion contribution and flux motion index. The next step was a correlation analysis with the glycated hemoglobin level.
Results. There were several correlations of the spectral LDF indicators with the level of glycated hemoglobin (Table 1). Thus, a negative correlation with the level of glycated hemoglobin was observed for the flux motion index (p=0.04) and the contribution of slow flux motion (p=0.03). On the contrary, for the contribution of pulse flux motion, there was detected a positive correlation with the level of glycated hemoglobin (p<0.01) (Fig. 1).
Conclusion. Correlations of LDF indicators with the level of glycated hemoglobin can be explained with the correlation of the diabetic microangiopathy progression with the effectiveness of glycemic control. Hyperglycemia is a key pathogenic factor of type 2 diabetes mellitus and its complications. Consequently, in patients with ineffective or less effective glycemic control, a more significant development of diabetic microangiopathy should be expected. An increase in the contribution of pulse flux motion in the laser Doppler flowmetry use guidelines is regarded as an increase in the role of the pulse wave in microcirculatory blood flow modulation. The cause of the latter is most likely a more intensive remodeling of the walls of arterioles against the background of a higher frequency of hyperglycemia episodes. The negative correlation of the contribution of slow flux motion can be explained by a violation of the local mechanisms of microcirculation modulation. The cause of this disorder is the morphofunctional restructuring of the microvessels themselves, the defeat of smooth myocytes in the wall of arterioles and venules, including pacemaker cells, with a violation of the automatic contractile activity of smooth myocytes, as well as endothelial. These factors lead to a shift in the balance of regulation towards systemic factors, which is reflected in the decrease of the flux motion index. A decrease in the flux motion index is regarded as a microcirculation deficiency, which was detected in all patients with type 2 diabetes mellitus. Thus, correlations of the spectral LDF indicators with the level of glycated hemoglobin corresponds to modern ideas about the pathogenesis of diabetic microangiopathy in type 2 diabetes mellitus. These data can be an additional argument in favor of the further development of improving laser Doppler flowmetry using for the tasks of non-invasive diagnosis of microvascular disorders in patients with type 2 diabetes mellitus. The reported study was funded by RFBR, project number 19-315-90080.
