The physiological role and clinical relevance of circulating secreted protein acidic and rich in cysteine (SPARC, or osteonectin) is still poorly understood. This study investigated the correlation between circulating SPARC and metabolic variables, including glucose and glycosylated haemoglobin (HbA_1c), during a diet and exercise modified weight reduction intervention programme. Changes in plasma SPARC levels and several metabolic variables were analysed in asymptomatically obese, nondiabetic, male subjects before and after weight reduction intervention. Body mass index and blood pressure, serum cholesterol and HbA_1c levels were all significantly reduced after weight reduction intervention. Multiple regression analysis demonstrated that changes in SPARC levels were significantly and positively correlated with HbA_1c. The relationship between SPARC and HbA_1c may merit further investigation with regard to its association with postprandial or long-term glucose variation in obese male subjects.