If you have diabetes and test your blood with a glucose meter and glucose testing strips, taking an excess of vitamin C may cause a false “low” blood sugar reading. That’s because the vitamin interferes with an enzyme in the test strip. If you have diabetes, you may want to steer clear of supplements. Instead, consider getting your daily dose of vitamin C directly from foods rich in this vitamin. That would include citrus fruits and berries (just remember to follow your doctor’s dietary recommendations when consuming foods naturally high in sugar) and a variety of vegetables. If you still want to take a supplement, use a time-release form of vitamin C and stick to about 250 mg daily.
Always check with your doctor if you have a health condition before taking any supplements.