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We compared skin and plasma measurements of advanced glycation end products (AGEs), with particular focus on their levels in the presence of hypertension or diabetes and prediabetes and their associations with arterial stiffness in outpatients with suspected or diagnosed hypertension.
Skin AGEs accumulation was measured as autofluorescence on the left forearm using the skin autofluorescence Reader and expressed in arbitrary units in the range from 0 to 25. Plasma AGEs concentration was measured by the enzyme-linked immunosorbent assay kits and logarithmically transformed for statistical analysis. Arterial stiffness was assessed by carotid-femoral pulse wave velocity (PWV) using the SphygmoCor system (Sydney, Australia).
The 218 participants (96 [44.0%] men, mean age 51.9 years), had a mean skin and plasma AGEs of 1.89 arbitrary units and 4.47 ug/ml, respectively, and carotid-femoral PWV of 8.0 m/s. Skin autofluorescence was significantly correlated with plasma AGEs in diabetic or prediabetic patients (n=31, r=0.37, P=0.04), but not in subjects with normoglycemia (n=187, r=-0.47, P=0.52) Nonetheless, both measurements were significantly (P≤0.001) higher in men (2.00 arbitrary units and 6.73 ug/ml, respectively) than women (1.81 arbitrary units and 3.60 ug/ml, respectively) and in diabetic or prediabetic (2.03 arbitrary units and 6.61 ug/ml, respectively) than normoglycemia subjects (1.87 arbitrary units and 4.17 ug/ml, respectively), but not in hypertensive (n=105) than normotensive subjects (n=113, P=0.35). In adjusted multiple regression analyses, plasma AGEs concentration was significantly associated with PWV in all subjects (β=0.44 m/s for each 10 - time increase; P=0.04) and in subgroups of men, diabetes and prediabetes (β=0.12 to 0.55 m/s for each 10 - time increase; P≤0.02).
In conclusion, although skin and plasma AGEs were similarly associated with gender and diabetes or prediabetes, they might measure something different and have different clinical relevance, such as for arterial stiffness.