Long-term effect of Chinese herbal medicine Tianqi Capsule on the incidence of diabetes: an 8-year cohort study protocol

Background: The rapid growth of type 2 diabetes mellitus (T2DM) remains a big challenge for clinicians worldwide. Traditional Chinese medicine may bring a new approach for solving this problem. The Tianqi Capsule Diabetes Prevention Study (REDUCES Study) reported that 1 years of therapy with Tianqi capsule reduced the risk of diabetes by 32.1% compared with the placebo. Here we aimed to assess the long-term effect of Tianqi capsule on prevention of T2DM in people with impaired glucose tolerance after discontinuation of active intervention. Methods/design: 420 subjects will be followed-up for 8 years to assess the long-term effect of Tianqi capsule intervention. The causes of death and the status of living subjects will be investigated. Follow-up data for living subjects will be collected by personal interview and clinical examination and medical record review to determine diabetes status. Questionnaires will be given to all the subjects to investigate the factors that probably affect the diabetes status during the 8-year of discontinuation of intervention. The primary outcome is the incidence of T2DM, and the secondary outcomes are body mass index, blood glucose, blood lipids and blood pressure. The Cox proportional hazards model will be used to estimate the hazard ratio for diabetes incidence. Analyses will be done with SAS 8.2 software package. Discussion: Results from this study may provide evidence for the long-term efficacy of Tianqi capsule in patients with prediabetes. The findings will provide a basis for further confirmatory studies. Ethics: The protocol has been approved by the Medical Ethics Committee of Guang’anmen Hospital of China Academy of Chinese Medical Sciences (approval number 2016-046-KY-01). Study registration number: ClinicalTrials.gov; NCT02848053.