Ascorbic acid status in diabetes mellitus

Abstract

Glucose and ascorbic acid share a common transport mechanism in human leukocytes and fibroblasts. To test the hypothesis that chronic, prolonged hyperglycemia may be associated with intracellular deficiency of ascorbic acid, we have compared the plasma and leukocyte ascorbic acid levels of 57 ambulatory diabetic patients (30 females, 27 males) to those of control subjects matched for sex, age and smoking habits. All subjects were in a good nutritional state and were not taking vitamin supplements or drugs known to affect ascorbic acid levels. There was no significant difference in plasma and leukocyte ascorbic acid levels between the groups. However, leukocyte ascorbic acid levels tended to be lower in insulin-dependent diabetics than in controls or non-insulin dependent diabetics. In diabetics, plasma ascorbic acid levels were negatively correlated with the glycosylated hemoglobin fraction (p=0.07). In this study, the observations by others, that diabetics have deficient plasma and leukocyte ascorbic acid levels was not confirmed. However, both diabetics and controls had significantly higher plasma and leukocyte ascorbic acid levels than reported in other studies. This discrepancy can be explained by the high ascorbic acid content of the Israeli diet. The negative correlation between glycosylated hemoglobin fraction and plasma ascorbic acid levels suggests that poor glycemic control may contribute to deficient leukocyte and ascorbic acid levels of diabetic patients.