CAMBRIDGE, UNITED KINGDOM. Researchers at Cambridge University have confirmed that diabetics have low blood levels of vitamin C. They conclude that these low levels are not a consequence of diabetes, but rather that a low vitamin C level is a risk factor for diabetes. Their conclusions are based on a study of 2898 men and 3560 women between the ages of 45 to 75 years. The participants underwent a clinical examination and had blood samples analyzed for vitamin C content and level of HbA1c (hemoglobin A1c). The level of HbA1c is an important indicator of glucose control. Nondiabetics have levels below 7 per cent (of total hemoglobin) while diabetics and people with poor glucose control (hyperglycemia) can have levels as high as 10-12 per cent. The researchers found that people with previously undiagnosed hyperglycemia had low vitamin C levels. An increase in vitamin C level of just 20 micromol/L was associated with a reduction in the risk of undiagnosed hyperglycemia by almost one third. An extra 20 micromol/L of vitamin C in the blood can be obtained by eating just one orange a day (vitamin C content = 65 mg). The researchers conclude that "dietary measures to increase plasma vitamin C may be an important public healthy strategy for reducing the prevalence of diabetes".
Sargeant, Lincoln A., et al. Vitamin C and hyperglycemia in the European Prospective Investigation into Cancer - Norfolk (EPIC-Norfolk) study. Diabetes Care, Vol. 23, June 2000, pp. 726-32