Abnormal immune functions of polymorphonuclear (PMN) cells occur in a variety of pathophysiological conditions. There exists a close link between glucose metabolism and PMN functions. The aim of this study was to assess the effect of short-term hyperglycemia and/or hyperinsulinemia on phagocytosis and respiratory burst of PMN cells in healthy subjects in vivo. The study was performed on 12 healthy subjects (mean age, 26.9+/-1.6 years; body mass index, 24.4+/-0.84 kg/m(2)). Acute hyperglycemia and/or hyperinsulinemia was induced by three 4-hour-long clamp studies-hyperglycemic hyperinsulinemic clamp (HHC), hyperinsulinemic euglycemic clamp (HEC), and isolated hyperglycemic clamp with insulin secretion blockade (HGC). Polymorphonuclear cell phagocytosis and PMN cell respiratory burst (mean percentage and mean fluorescent intensity of phagocyting/activated PMN cells, phagocytic, and respiratory burst indexes) were evaluated by flow cytometry under basal and stimulated conditions. Results detected during clamp studies were compared with those found during a control study with saline infusion. Significant reductions in the mean percentage of phagocyting cells measured under basal conditions after the HHC (6.7%+/-1.3% vs 12.1%+/-4.3%; P<.05) and HGC (4.5% +/-1.8% vs 9.9%+/-2.1%; P<.05) were found in comparison with the pre-clamp study period; however, these results did not differ significantly from those detected during the control clamp (CC) study. Significantly higher phagocytic (115.1+/-65 vs 35.8 +/-18.6; P<.05) and respiratory burst indexes (16.5+/-3 vs 10.1+/-1.4; P<.05) measured under basal conditions were found after HEC in comparison with the pre-clamp data. However, these data did not differ significantly from those found after the CC study. No significant differences in other parameters of detected PMN cell immune functions were found after HHC, HEC, and HGC. In conclusion, immune functions of PMN cells were not significantly influenced by short-lasting hyperglycemia and/or hyperinsulinemia induced in vivo by clamp techniques in healthy subjects compared to changes induced by the CC study. Further studies on the short-term effect of glucose metabolism on PMN functions in diabetic patients should be considered necessary.