Circulating acute phase reactive proteins as indicators of infection in poorly controlled diabetes mellitus

Serum levels of six acute phase proteins (APP)--C-reactive protein (CRP), serum amyloid A (SAA), alpha 1-antitrypsin, haptoglobin and complement fractions C3 and C4--were serially studied in 24 patients with poorly controlled diabetes mellitus, ten of whom had unequivocal evidence of an underlying infection. In diabetic patients without infection, no change in APP levels was noted suggesting that hyperglycaemia per se does not quantitatively influence the acute phase response. No correlation between the presence of infection, and fever, leukocytosis, a raised erythrocyte sedimentation rate, or serum levels of alpha 1-antitrypsin, haptoglobin or complement was apparent in these patients. However, serum CRP and SAA were initially increased 10-100 times above normal in diabetic patients with an underlying infection (P less than 0.01); during the following week circulating levels of CRP and SAA decreased steadily in response to the infection being brought under control. We conclude that serial measurement of CRP and/or SAA is a sensitive, albeit non-specific, parameter to detect and monitor the activity of infection in patients with diabetes.