Vitamin C, Insulin Good for Diabetes

COVENTRY, England—According to a study at Warwick Medical School, long-lasting high blood sugar in type 1 diabetic patients induces long-term alterations in endothelial cells, which may contribute to endothelial dysfunction and is interrupted only by both glucose and oxidative stress normalization (J Clin Endocrino Metab. 2009) (DOI:10.1210/jc.2009-0762). A total of 10 healthy subjects and three subgroups of 10 type 1 diabetic subjects were enrolled in (1) patients within one month of diagnosis; (2) patients between 4.5 to 5.2 years from diagnosis and with HbA1c levels 7 percent since diagnosis; (3) patients between 4.8 to 5.4 years from diagnosis and with HbA1c levels greater than 7 percent since diagnosis. Each patient participated in three experiments: (a) 24 hour insulin treatment, achieving a near-normalization of glycemia, together with the addition of the antioxidant vitamin C during the last 12 hours; (b) 24 hours vitamin C treatment with insulin treatment for the last 12 hours; (c) treatment with both vitamin C and insulin for 24 hours.

Endothelial function, as measured by flow-mediated vasodilation (FMD) of the brachial artery and levels of nitrotyrosine, an oxidative stress marker, were normalized by each treatment in subgroups 1 and 2. In the third subgroup, neither glucose normalization nor vitamin C treatment alone was able to normalize endothelial dysfunction or oxidative stress. Combining insulin and vitamin C, however, normalized endothelial dysfunction and nitrotyrosine.