Effects of Vitamin C Supplementation on Glycemic Control and Cardiovascular Risk Factors in People With Type 2 Diabetes: A GRADE-Assessed Systematic Review and Meta-analysis of Randomized Controlled Trials

This review (28 RCTs; n=1,574) found very low certainty evidence that vitamin C supplementation was associated with improvements in HbA1c (mean difference −0.54% [95% CI −0.90, −0.17]; P=0.004); improvements in systolic and diastolic BP were also noted.

SPS commentary:

The authors note that the majority of the included studies were small and short-term (<6 months), and conclude that while evidence suggests vitamin C supplementation may improve glycaemic control and blood pressure in people with type 2 diabetes in the short-term, larger and longer-term studies are required to confirm or refute these findings, and before any recommendations can be made.

Diabetes Care