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The Zn/Cu ratio was examined in the serum of three groups of persons: healthy volunteers, diabetic patients on diabetic diet (NIDDM), and diabetic patients on diabetic diet and insulin (IDDM). Zinc, copper, the Zn/Cu serum ratio, and the blood glucose level were determined during fasting and 2 h after breakfast. Zn and Cu serum levels in NIDDM and IDDM patients were decreased. The Zn/Cu ratio was higher in both groups of diabetic patients. These changes in the Zn and Cu levels as well as in the Zn/Cu ratio were not related to chronic diabetic complications.

We evaluated the ability of zinc to modulate the superoxide anion released by isolated, phorbol myristate acetate (PMA)-stimulated polymorphonuclear leukocytes (PMNs). In the presence of zinc at physiological level (20 micromol/l), PMNs released 20% less superoxide anions than untreated cells, whereas at higher zinc concentration (200 micromol/l), a 40%-increase in superoxide anion production was detected. The direction (suppression or stimulation) of superoxide anion generation was dependent upon extracellular zinc level and did not discriminate type 1 and 2 diabetic subjects from normal controls. The mechanism(s) of dose-dependent pro- and antioxidative effects of zinc on isolated PMNs in vitro as well as the implication of this finding for the modulatory effect of Zn on PMN-superoxide anion production in vivo need further investigation.

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