BACKGROUND: Type 2 diabetes is characterized by increased acute phase serum proteins. They are also risk factors for cardiovascular disease. We wanted to study how improvement of glycemic control with pioglitazone or glibenclamide affects their serum concentrations. MATERIALS AND METHODS: A total of 59 patients with Type 2 diabetes (age 57.3+/-1.2 yr, glycosylated hemoglobin (HbA1c) 8.3+/-0.7%, body mass index (BMI) 31.4+/-0.8 kg/m2) participated in the study. They were previously treated either with diet alone or in combination with one oral antihyperglycemic medicine. After a 1-week lead-in period on diet only, the patients were randomized to pioglitazone or glibenclamide. Blood samples for alpha-1-acid glycoprotein (A1GP), Creactive protein (CR P) and serum amyloid A (SAA) were taken before the treatments and during the therapy after 20 and 52 weeks. RESULTS: Baseline A1GP correlated with CR P (r=0.70, p<0.001) and fasting glucose (r=0.32, p<0.02). Baseline CR P correlated with HbA1c (r=0.26, p<0.05) and insulin (r=0.37, p<0.01). The anti-hyperglycemic effect was comparable with HbA1c levels decreasing both in the pioglitazone (from 8.18+/-0.09% to 7.63+/-0.17%, p<0.01) and glibenclamide (from 8.35+/-0.12% to 7.77+/-0.16%, p<0.01) groups. Pioglitazone treatment was associated with a reduction in A1GP at 20 weeks (p<0.001) and at 52 weeks (p<0.05) as compared to baseline. The significance remained also after comparison to glibenclamide therapy (p<0.001 and p<0.05, 20 and 52 weeks respectively). CR P was also more reduced in the pioglitazone group at 20 weeks of treatment (p<0.05). CONCLUSIONS: Inflammatory factors and markers of hyperglycemia are associated in patients with Type 2 diabetes. Pioglitazone treatment results in reduced A1GP concentration suggesting an anti-inflammatory effect.