Lymphocyte and Plasma Vitamin C Levels in Type 2 Diabetic Patients With and Without Diabetes Complications
- Hiroshi Yamada, MD1,
- Kaoru Yamada, MD2,
- Masako Waki, MD3 and
- Keizo Umegaki, PHD4
- 1General Clinical Research Center, Hamamatsu University School of Medicine, Hamamatsu, Japan
- 2Department of Health and Preventive Care Center, Shizuoka City Hospital, Shizuoka, Japan
- 3Department of Endocrinology and Metabolism, Shizuoka City Hospital, Shizuoka, Japan
- 4National Institute of Health and Nutrition, Toyama, Shinjuku-ku, Tokyo, Japan
- Address correspondence and reprint requests to Dr. Hiroshi Yamada, MD, Hamamatsu University School of Medicine, General Clinical Research Center, 1-20-1 Handayama, Hamamatsu 431-3192, Japan. E-mail: hyamada{at}hama-med.ac.jp
Diabetes has been considered to be associated with oxidative stress. It has been suggested that increased free radicals and decline of antioxidant defense mechanisms induce diabetic micro- and macrovascular complications (1–3). Vitamin C is one of the major antioxidants and is detected in various blood components (4). However, measurements of vitamin C levels have shown inconsistent results, and the interpretation of vitamin C levels in diabetes as an antioxidant biomarker has not been clarified (5–8). In this study, we investigated the lymphocyte and plasma vitamin C levels in type 2 diabetic patients with and without diabetes complications.
RESEARCH DESIGN AND METHODS
Forty-one patients with type 2 diabetes (63 ± 8.9 years [mean ± SD]; 25 men and 16 women) attending the Department of Endocrinology and Metabolism at Shizuoka City Hospital were recruited. Type 2 diabetes was diagnosed according to the American Diabetes Association criteria. The duration of illness was 11 ± 8.3 years, fasting plasma glucose was 137 ± 43 mg/dl, and HbA1c levels were 7.1 ± 1.0%. Twenty-six patients had diabetes complications with neuropathy, retinopathy, or nephropathy, and 15 patients had no complications. Both diabetic groups were matched by age, sex, fasting plasma glucose, and HbA1c level (63 ± 9.7 years, 18 men and 8 women, 137 ± 45 mg/dl, and 7.2 ± …
