**4.1 Type 2 diabetes (T2D)**

Patients with type 2 diabetes received chewable vitamin C tablets (1000 mg/day) for 45 days in a randomized controlled trial [41]. At the end of the study, there was a remarkable reduction of both systolic and diastolic blood pressures among the vitamin C group compared to the placebo group. The mechanism behind is not clearly elucidated. However, other parameters such as hip and waist circumferences, body weights, and BMI were relatively the same compared to the placebo group.

Although no overall benefit of vitamin C was noted on glucose level and HbA1c and insulin concentrations in a systematic review and a meta-analysis of RCTs [43], the blood glucose levels were significantly reduced among diabetic patients on vitamin C supplementation for a longer duration (>30 days). Nevertheless, the dosage was not considered in the analysis hence the need to interpret the results carefully. However, this shows that the duration of supplementation and not necessarily the dosage may determine the impact of vitamin C on type-2 diabetes.
