Effects of Shenlian formula on microbiota and inflammatory cytokines in adults with type 2 diabetes: a double-blind randomized clinical trial.

Objectives: To observe the efficacy of Shenlian formula (SL formula, ), which consist of Huanglian () and Renshen (), in the treatment of type 2 diabetes mellitus (T2DM) and explore the effects on gut microbiota and serum inflammatory cytokines.

Methods: In a double-blind, randomized, placebo-controlled parallel-group clinical trial, 31 adults with T2DM were randomly allocated to receive the SL formula or placebo for 12 weeks. Body mass index (BMI), blood lipid indices, glycemic biomarkers including glycated hemoglobin (HbA1C), fasting plasma glucose (FPG), postprandial blood glucose (PBG), fasting insulin levels (FIL), fasting C-peptide (C-P), homoeostasis model assessment for insulin resistance (HOMA-IR) and inflammatory cytokines were assessed at baseline and 12 weeks. The contents of gut microbiota were determined by pyrosequencing of the V3-V4 regions of 16S rRNA genes.

Results: Sixteen cases were allocated in the treatment group and 15 in the placebo group. Compared with the placebo, SL formula resulted in a higher significant reduction in PBG [(?1.318 ± 0.772)(?0.008 ± 1.404) mmol/L, 0.003], BMI [(?0.611 ± 0.524)(0.957 ± 2.212) kg/m, 0.01], FIL [(?1.627 ± 6.268)(3.976 ± 6.85) μIU/mL, 0.02], HOMA-IR [(?0.530 ± 1.461)(1.511 ± 2.288), 0.006], and C-reactive protein (CRP) [(?1.307 ± 0.684)(0.828 ± 0.557) mg/L, 0.04]. In terms of gut microbiota, compared with the placebo, the SL formula resulted in a significant decrease in species richness and evenness.

Conclusions: The SL formula showed the efficacy to improve postprandial blood glucose, insulin resistance, BMI and CRP levels. In addition, it could reduce the total number, richness and evenness of species, meanwhile increase the abundance of probiotics to modulate the structure of gut microbiota in patients with T2DM. However, further studies are required for exploring the deeper mechanism of TCM on gut microbiota.