Endothelial dysfunction and arterial stiffness in normotensive normoglycemic first degree relatives of diabetic patients are independent of the metabolic syndrome

Background and aim: The aim of the present study was to investigate endothelial function and arterial stiffness in normotensive normoglycemic first-degree relatives (offspring) of diabetic subjects and to explore the relationship with the metabolic syndrome and its components. Methods and results: Forty-five healthy normotensive normoglycemic subjects (aged 18-42 years), 29 first-degree relatives of diabetic subjects (FDR) and 16 with no parental history of type 2 diabetes mellitus were studied. Endothelial function was measured as flow-mediated dilation of the brachial artery (FMD) and arterial stiffness as carotid-femoral pulse wave velocity (PWV). Insulin resistance was calculated by homeostasis model assessment (HOMA). Plasma levels of inflammation markers (hsCRP, TNF-α, IL-1β, CD40L, VCAM, and ICAM) were evaluated. Normotensive normoglycemic FDR presented a 33% lower flow-mediated dilation than the control group (9.8 ± 5.2 vs. 16.2 ± 7.6%, p < 0.01). FMD was reduced in FDR, with or without insulin resistance, whereas arterial stiffness was significantly increased only in FDR with insulin resistance. To investigate the role of FDR status independently of altered components of the metabolic syndrome, subjects with no altered components of the metabolic syndrome were compared according to their FDR status: FDR subjects with no altered components of the metabolic syndrome presented a blunted endothelial function (lower FMD: 11.2 ± 1.6 vs. 16.8 ± 2.0%, p < 0.05) and stiffer large arteries (higher PWV: 9.6 ± 0.3 vs. 8.8 ± 0.3 m/s, p < 0.05) than controls. Conclusion: Normoglycemic first-degree relatives of diabetic subjects have blunted endothelial function and increased stiffness of the large arteries. These alterations are already present at a very young age, before any alteration in glycemic control or blood pressure values can be detected, and are independent of the presence of the metabolic syndrome and its altered components.