Gut microbiome-related effects of berberine and probiotics on type 2 diabetes (the PREMOTE study)

Human gut microbiome is a promising target for managing type 2 diabetes (T2D). Measures altering gut microbiota like oral intake of probiotics or berberine (BBR), a bacteriostatic agent, merit metabolic homoeostasis. We hence conducted a randomized, double-blind, placebo-controlled trial with newly diagnosed T2D patients from 20 centres in China. Four-hundred-nine eligible participants were enroled, randomly assigned (1:1:1:1) and completed a 12-week treatment of either BBR-alone, probiotics+BBR, probiotics-alone, or placebo, after a one-week run-in of gentamycin pretreatment. The changes in glycated haemoglobin, as the primary outcome, in the probiotics+BBR (least-squares mean [95% CI], −1.04[−1.19, −0.89]%) and BBR-alone group (−0.99[−1.16, −0.83]%) were significantly greater than that in the placebo and probiotics-alone groups (−0.59[−0.75, −0.44]%, −0.53[−0.68, −0.37]%, P < 0.001). BBR treatment induced more gastrointestinal side effects. Further metagenomics and metabolomic studies found that the hypoglycaemic effect of BBR is mediated by the inhibition of DCA biotransformation by Ruminococcus bromii. Therefore, our study reports a human microbial related mechanism underlying the antidiabetic effect of BBR on T2D. (Clinicaltrial.gov Identifier: NCT02861261).


Statistics
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MRI-based neuroimaging
The study sample size calculations were based on previously published data (Ref: Tonucci LB, et al. Clin Nutr. 2017;36:85-92, and Zhang Y, et al. J Clin Endocrinol Metab. 2008;93:2559-2565. and the primary outcome in the current study, which is change in HbA1c. The sample size estimation is within the framework of generalized estimating equations (GEE) models (Ref: Jung SH, et al. Stat Med. 2003;22:1305-1315. For primary outcome: The outcome variable is HbA1c with a baseline measurement and the follow-up at 13 weeks after intervention initiation. The aim of the study is a comparison of slopes in repeated measurements with equal allocation in 4 treatment arms. Based on the preliminary data, with a sample size of 360 study participants, this study will have a power of 86% (based on a two-sided test, ! = 5%). We have conservatively assumed that the overall dropout rate will be 10% during the 13-week study period. To account for loss to follow-up, the power will be 86% if 400 study subjects are recruited. Detailed sample size calculation was summarized in Method and Study protocol.
Statistical analyses for clinical data includes all subjects who are randomized independent of whether they received study treatment or not. Samples that were not paired pre and post treatment would not be included in the paired Wilcox study and multi-omics analysis.
For clinical study, a total of 566 patients were screened for eligibility from August 18, 2016 to July 18, 2017, of whom 409 participants underwent randomization: 106 were randomly assigned to the Prob+BBR group, 102 to Prob group, 98 to the BBR group, and 103 to the Plac group. For the in vitro studies, at least 3 replicates in 3 independent experiments were performed in each group.
Participants were randomly assigned into the treatment groups. The randomization procedure was stratified by age, in a block size of 8 and generated utilizing a validated interactive Web-based Response System (IWRS) which was maintained by an independent data manager.
The study personnel and participants were blinded to the assignment of treatment groups. The study investigators and statisticians were all blinded during the study procedure before the database lock, and were unblinded after database unblinding procedure.