Recent studies have shown a link between type 2 diabetes mellitus (T2DM) and the gut microbiota, by way of numerous molecular mechanisms. As such, it stands to reason that modulating the gut microbiota using probiotics could help in managing T2DM.
Based on this, researchers at Iran's Tabriz University of Medical Sciences conducted a trial to assess the effect of L. casei on glycaemic control and serum sirtuin1 (SIRT1, a protein inversely associated with insulin resistance) and fetuin-A (a blood protein directly associated with insulin resistance) in T2DM patients.
They recruited 40 T2DM patients and divided them equally into an intervention group and a placebo group. Those in the former group were each given a daily capsule containing 108 CFU (colony-forming units) of L. casei, while those in the latter group were given daily capsules containing maltodextrin.
The treatment period lasted eight weeks, after which blood samples were collected from the study subjects, who were assessed by an endocrinologist at the beginning and end of the trial.
The researchers then reported that fasting blood sugar, insulin concentration, and insulin resistance in the supplemented group had been reduced significantly, compared with the placebo group.
Furthermore, those who had taken the probiotic capsules also saw their glycated haemoglobin lowered, albeit to a non-statistically significant extent.
When it came to SIRT1 and fetuin-A levels, L. casei supplementation was reported to have significantly increased SIRT1 and significantly decreased fetuin-A levels by the end of the trial.
In addition, L. casei supplementation also "significantly affected dietary intake and anthropometric indexes, including weight, BMI, and waist circumference" in the supplemented study subjects.
The researchers attributed these observations to the impact of probiotics on gut microbial composition, which can in turn affect appetite and food intake, as well as weight and body composition.
This modulation of the gut microbiota allows probiotics to affect an individual's energy balance and / or metabolism, mainly due to the production of SCFAs (short-chain fatty acids) through the fermentation of indigestible polysaccharides.
More microbiome mechanisms
The syudy also showed that probiotics provided benefits in terms of the patients' weight, along with their BMI and waist circumference.
In conclusion, the researchers wrote: "L. casei supplementation affected SIRT1 and fetuin-A levels in a way that improved glycemic response in subjects with T2DM.
"Taking into account the metabolic impacts of SIRT1 and fetuin-A, management of their levels introduces a new known mechanism of probiotic action in diabetes management.
"The results of the present trial help us to reveal a new mechanism of probiotic action in diabetes and its related metabolic disorders.
"Besides, as shown in this study, the positive effects of probiotics on body weight could be translated into favourable metabolic effects and have beneficial effects on the homeostasis of glucose."
Source: Iranian Biomedical Journal
"The Effects of Lactobacillus casei on Glycemic Response, Serum Sirtuin1 and Fetuin-A Levels in Patients with Type 2 Diabetes Mellitus: A Randomized Controlled Trial"
Authors: Leila Khalili, et al.