Levels of plasma pentosidine, a well-known AGE, were measured in type 2 diabetic patients in varying states of metabolic control to verify possible relationships between this parameter and traditional metabolic control parameters such as HbA1c and plasma glucose levels. At baseline, mean values of fasting plasma glucose, HbA1c and pentosidine were significantly higher in diabetic patients than those of controls, confirming patients' poor glycemic control. After ten months, patients with good metabolic control achieved showed near-normal HbA1c levels and reduced but not normalized pentosidine levels. Significant differences were found in the mean percentage decrease in the parameters. Regarding linear correlation, HbA1c levels only showed a positive relationship with plasma glucose values at baseline. Patients affected by chronic complications showed higher levels of pentosidine than those without complications. Thus, pentosidine plasma levels may be used to evaluate very long-term metabolic control in diabetic patients. In addition, a period of ten months of acceptable metabolic control is not enough to normalize pentosidine levels in diabetics, thus emphasizing the need for a longer period of improved metabolic control to reduce both this parameter and the burden of chronic diabetic complications.