Probiotics 'had no statistically significant benefits' for managing diabetic symptoms – RCT
The study was funded by a few organisations in China, which included Sichuan University and the Health Research of Cadres in Sichuan province.
“[Our] 16-week intervention study demonstrated that probiotic supplementation had some effects on fasting blood glucose, glycated haemoglobin, triglycerides, and weight in patients with type 2 diabetes.
“However, these effects did not reach statistical significance when compared to the control group, and no clear improvements were observed in other lipid parameters,” wrote researchers in Frontiers in Endocrinology.
These results contrast with findings from recent studies that have highlighted the antidiabetic potential of probiotic supplementation.
Previously, probiotics have shown promising effects on the glycaemic control and lipid profiles of patients with type 2 diabetes. Multiple studies have reported significant reductions in HbA1c and fasting insulin levels following probiotic supplementation. Fasting plasma glucose levels were also found to decrease significantly in some trials.
As for lipid profiles, previous research has also demonstrated potential in lowering total cholesterol, triglycerides, and LDL-cholesterol, while increasing HDL-cholesterol.
While encouraging, these findings were not always statistically significant, and existing research tends to be limited by small cohort sizes and brief intervention periods.
Considering these factors, researchers conducted a randomised controlled trial that studied the effects of probiotics on type 2 diabetes patients.
The objective was to evaluate the effectiveness of probiotics on glycaemic control and other diabetes-related outcomes in patients with type 2 diabetes patients.
Primary outcomes were changes in HbA1c and fasting blood glucose (FBG) levels post-intervention – HbA1c shows the average blood sugar level was over the past two to three months, while FBG measures blood glucose after at least 8 hours without food.
Investigating the comparative effects of inactivated and active probiotics
This double-blind, placebo-controlled, randomised clinical trial was conducted at the West China Hospital, Sichuan University.
There were 213 type 2 diabetic patients, aged 18 years and older, recruited for the trial.
They were randomly assigned to two groups.
The probiotic group had 103 participants and the placebo group had 110 participants.
The probiotic group received 25 ml of a probiotic beverage containing more than 10^8 CFU/mL of Lactobacillus, administered four times daily.
An equal volume of inactivated Lactobacillus was administered to the placebo group, which also ingested the same volume of inactivated Lactobacillus.
The probiotics were supplied by Zhejiang Kunyue Pharmaceutical Co., Ltd.
The results
After 16 weeks of treatment, the probiotic group showed mean reductions in HbA1c and FBG by 0.44% and 0.97% respectively.
The placebo group showed mean reductions in HbA1c and FBG by 0.33% and 0.9% respectively.
Mean total cholesterol was reduced by 0.28mmol/L for the probiotic group and 0.19 mmol/L for the placebo group.
As for mean weight reduction, the probiotic group showed a decrease of 3.43kg while the placebo group decreased by 0.87kg.
But these changes were not statistically significant, said researchers.
“Overall, 16-week probiotic supplementation showed no beneficial effects on glycaemic control, lipid profiles, or weight,” concluded the researchers.
Potential of inactive bacteria
There were partial improvements in blood glucose and lipid levels in the placebo group, which can be attributed to the placebo effect.
Another contributing factor could be the use of low-concentration inactivated bacteria in the placebo.
Previous studies have shown that inactivated probiotics may play a role in weight reduction and cholesterol lowering, potentially through modulation of gut microbiota.
Furthermore, peptidoglycan, a component of bacterial cell walls, may be instrumental in the regulation of GLP-1 secretion, enhancement of insulin sensitivity, and improvement of glucose tolerance.
Thus, the therapeutic potential of dead bacteria in the treatment of diabetes should not be dismissed, and future studies should consider including groups that receive dead bacteria along with blank control groups to further explore this possibility.
Researchers concluded that probiotics as an alternative approach for diabetes management remains uncertain.
“Further research involving longer follow-up periods, multiple centres, diverse subject groups, and a variety of probiotic strains is needed to comprehensively assess the efficacy of probiotic supplementation in type 2 diabetes management,” said the researchers.
Source: Frontiers in Endocrinology
DOI: https://doi.org/10.3389/fendo.2024.1440286
“Effect of probiotics on glycemic control and lipid profiles in patients with type 2 diabetes mellitus: a randomized, double blind, controlled trial”
Authors: Xuchao Peng, Hong Xian et al.
