A systematic review of vanadium oral supplements for glycaemic control in type 2 diabetes mellitus

Objective: To assess the effectiveness of oral vanadium supplementationfor glycaemic control in type 2 diabetes by conducting a systematicreview of the literature. Design and Methods: Eligible studies were identified by searching14 databases using standardized terms. Experts, study authorsand manufacturers were also contacted. Hand-searching was notundertaken. Selection criteria for inclusion in the review werecontrolled human trials of vanadium vs. placebo in adults withtype 2 diabetes of minimum 2 months duration, and a minimumof 10 subjects per arm. Data extraction, assessment of studyquality and outcome analysis were undertaken by two independentreviewers. Results: One hundred and fifty one studies were found but nonemet the inclusion criteria. We proceeded to summarize the stateof existing evidence and plan for a future clinical trial byapplying revised, less restrictive criteria to our search, forclinical trials of 30–150 mg daily oral vanadium supplementationin diabetic humans. Only five were identified. These demonstratedsignificant treatment-effects, but due to poor study quality,must be interpreted with caution. Treatment with vanadium oftenresults in gastrointestinal side-effects. Conclusion: There is no rigorous evidence that oral vanadiumsupplementation improves glycaemic control in type 2 diabetes.The routine use of vanadium for this purpose cannot be recommended.A large-scale randomized controlled trial is needed to addressthis clinical question.