Subjects who develop diabetes have an increased cardiovascular risk even before the appearance of diabetes. The aim of this study was to investigate the glycaemic variability measured by continuous glucose monitoring (CGM CV%) in nondiabetic subjects with metabolic syndrome (MS) and to explore if glycaemic variability was associated with circulating levels of interleukin-6 (IL-6), a proinflammatory cytokine, or with an anti-inflammatory factor like adiponectin. Three groups of obese subjects with (MS+: 6m, 8f; BMI 33.1+/-1.4 mean+/-SEM) or without metabolic syndrome (MS-: 2m, 4f; BMI 29.2+/-2.2) and with MS associated with type 2 diabetes (MS/T2D: 3m, 5f; BMI 32.9+/-1.4) were investigated. The glycaemic variability was measured in all subjects in terms of CV% of the glycaemic values obtained every 3 min during the course of a 48 h CGM performed using a subcutaneous glucose sensor. The average CGM CV% increased from MS- group (21.1%) to the MS+ group (23.9%) and to the MS+/T2D group (27.4%) but it was not correlated to the CGM mean glycaemia (r=0.20; P=ns). In some instances, CGM CV% was found higher in MS+ subjects than in some MS+ T2D ones. Stepwise multiple correlation analysis showed that IL-6 predicted CGM CV% (R(2)=0.35, beta=0.13; P<0.05) independently from BMI, waist circumference, adiponectin and insulin concentrations. In conclusion, the CGM CV% may contribute to better describe the individual metabolic state and to understand the pathogenesis of endothelial dysfunction in non diabetic subjects with MS.