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 .
Supplementation of Vitamin C Reduces Blood Glucose and Improves Glycosylated Hemoglobin in Type 2 Diabetes Mellitus: A Randomized, Double-Blind Study
No study has ever examined the effect of vitamin C with metformin on fasting ( FBS ) and postmeal blood glucose ( PMBG ) as well as glycosylated hemoglobin ( HbA1c ) in the treatment of type 2 diabetes mellitus ( DM ) . The goal was to examine the effect of oral vitamin C with metformin on FBS , PMBG , HbA1c , and plasma ascorbic acid level ( PAA ) with type 2 DM . Seventy patients with type 2 DM participated in a prospect i ve , double-blind , placebo-controlled , 12-week study . The patients with type 2 DM were divided r and omly into placebo and vitamin C group of 35 each . Both groups received the treatment for twelve weeks . Decreased PAA levels were found in patients with type 2 diabetes mellitus . This level was reversed significantly after treatment with vitamin C along with metformin compared to placebo with metformin . FBS , PMBG , and HbA1c levels showed significant improvement after 12 weeks of treatment with vitamin C. In conclusion , oral supplementation of vitamin C with metformin  reverses ascorbic acid levels , reduces FBS , PMBG , and improves HbA1c . Hence , both the drugs in combination may be used in the treatment of type 2 DM to maintain good glycemic control
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 .