Overall , vitamin C did not modify glucose , HbA1c and insulin concentrations .
Meta-regression analyses showed that age was a modifier of the effect of vitamin C on insulin concentration .
Furthermore , the effect size was associated with baseline BMI and plasma glucose levels , and with the duration of the intervention .
In conclusion , greater reduction in glucose concentrations observed in patients with diabetes , older individuals and with more prolonged supplementation .
R and omised controlled trials ( RCTs ) have observed contrasting results on the effects of vitamin C on circulating biomarkers of glycaemic and insulin regulation .
The effect of aspirin and vitamins C and E on HbA1c assays.
BACKGROUND Aspirin ( ASA ) and vitamins C and E may inhibit non-enzymatic glycation in vivo and may also interfere with HbA(1c ) assays , masking true results . We investigated the effect of usual doses of ASA , vitamin C and E on HbA1c levels in a group of non-diabetic volunteers . METHODS A r and omized clinical trial was performed with 28 healthy non-diabetic individuals . Subjects were allocated to take ASA 200 mg/day , vitamin C 1 g/day , vitamin E 400 mg/day , or to a control group , for a period of 4 months . Blood sample s were collected at baseline and at monthly intervals for HbA1c analysis by HPLC Variant II ( BioRad ) , HPLC L-9100 ( Merck - Hitachi ) and Tina Quant HbA(1c ) II immunoassay ( Roche ) . RESULTS HbA(1c ) levels of the control , vitamin C and E groups did not change throughout the study , independently of the method used . HbA(1c ) measured by Hitachi L-9100 HPLC increased significantly ( P=0.033 ) at 4 months after ASA intake , although this increase was of only 0.17 % . CONCLUSIONS Treatment with vitamins C and E in pharmacological doses does not have any impact on HbA1c measurements in non-diabetic patients with the three methods employed . ASA induces a modest , not clinical ly relevant , increase in HbA1c levels with one of the methods
Overall , vitamin C did not modify glucose , HbA1c and insulin concentrations .
Meta-regression analyses showed that age was a modifier of the effect of vitamin C on insulin concentration .
Furthermore , the effect size was associated with baseline BMI and plasma glucose levels , and with the duration of the intervention .
In conclusion , greater reduction in glucose concentrations observed in patients with diabetes , older individuals and with more prolonged supplementation .
R and omised controlled trials ( RCTs ) have observed contrasting results on the effects of vitamin C on circulating biomarkers of glycaemic and insulin regulation .