Benefits of Vitamin Supplementation in Lowering Blood Glucose Remain Unclear

The journal Diabetology & Metabolic Syndrome has published a systematic review and meta-analysis of vitamins that have antioxidant potential and their use among patients who have type 2 diabetes (T2D). The findings are from 12 studies that looked at antioxidant outcomes. The vitamins that were studied most often included vitamins B, C, D, and E.

Vitamin E was related to significant reductions in blood glucose and glycated hemoglobin compared with the placebo. The researchers suggest that vitamin E may reduce damage incurred from free radicals on the functional and structural components of cells and vessel walls.

Vitamins C and E and glutathione, all of which are nonenzymatic antioxidants, seem to be able to interrupt free-radical chain reactions. There is intense interest in administering these vitamins in combination. Some evidence indicates that long-term use of dietary supplements, including multivitamin or mineral complexes, may improve blood pressure, cholesterol, C-reactive protein, high-density lipoprotein, the incidence of diabetes, and serum homocysteine. The researchers had insufficient data to make any conclusions about vitamin D supplementation.

Doses ranged from 500 to 3000 mg/day for vitamin C; 500 to 200,000 IU/day for vitamin D; and 400 to 1600 IU/day for vitamin E. Vitamin supplementation with vitamins C and E may help enhance antioxidant capacity and reduce diabetes complications.

Further studies are needed before clinical recommendations can be formulated, but these supplements are generally well tolerated, with few adverse effects, if any.