Fig. 7

The association between LDL concentration measured as weighted mean difference and various factors. Younger age (β = 2.85 CI 0.29, 4.82: p-value = 0.031), lower dose (β = 0.02 CI: 0.00, 0.05: p-value = 0.039), longer duration (β = − 1.16 CI − 2.17, -0.16: p-value = 0.027) and higher baseline HgA1C (β = − 20.77 CI − 41.32, − 0.22: p-value = 0.048) were advantageous circumstances for vitamin C effect