Microvascular Function in the Skin and the Retina in Insulin Resistant and in Type 2 Diabetic Subjects
Abstract Number: 1007-P
Authors: THOMAS FORST, GEORG MICHELSON, MATTHIAS M. WEBER, MICHAEL MITRY, THOMAS SCH[Ouml]NDORF, FLORIAN NOLDEN, EDA TARAKCI, ANDREAS PF[Uuml]TZNER
Institutions: Mainz, Germany, Erlnagen, Germany
Results: Endothelial dysfunction in type 2 diabetic patients was found to be closely associated with insulin resistance. Our study investigated the microvascular function in the skin and the retina in insulin resistant and in type 2 diabetic subjects.
54 subjects were included in the study. Subjects were divided into three groups, non-diabetic subjects with a HOMA score ≤ 2 (7 male, 11 female; age: 52.7±11.6 years; mean±SD), non-diabetic subjects with a HOMA Score > 2 (7 male, 11 female; age: 54.9± 8.7 years); and type 2 diabetic subjects (12 male, 6 female; age: 55.8±9.6 years). The microvascular response to ischaemia and the oxygenation in the skin was measured at the thenar surface using the technique of simultaneous micro-lightguide spectrophotometry and laserdopplerfluxmetry (O2C; Lea Medizintechnik, Giessen, Germany). Retinal mscanning was performed (Heidelberg Retina Flowmeter, Heidelberg Engineering) at baseline and after flicker light stimulation (10 Hz; Photo Stimulater 750, Siemens-Elema AB).
Skin blood flow was lower in insulin resistant subjects (IR) compared to control subjects (C), while diabetic subjects (D) were in between (C: 72.3±27.1 AU; IR: 48.2±21.2 AU, p<0.05; D: 66.8±41.9 AU, n.s.; p vs. C). The post-ischaemic hyperaemic response was slightly lower in the IR and the D group (C: 67.4±25.4 AU; IR: 55.1±33.9 AU, n.s.; D: 58.3±22.1 AU, n.s.), and postischaemic tissue oxygenation was lower in the IR and the D group (C: 73.2±6.2%; IR: 68.5±7.0 %, p<0.05; D: 63.6±18.3%, p<0.05). A slightly, even non-significant, higher increase in retinal microvascular blood flow after flicker stimulation was observed in the IR and D group (C: 9.02±15.3%; IR: 15.2±18.5 %, n.s.; D: 12.8±13.3 %, n.s.). No correlation was found between the microvascular response in the skin and in the retina.
Our study confirmed an impaired microvascular function in the skin in insulin resistant and in type 2 diabetic patients. In contrast, in these patients, the microvascular response in the retina was even exaggerated. Further research have to clarify if these differences in microvascular physiology are tissue dependent or due to the different stimulation techniques.