Holistic perspective of the role of gut microbes in diabetes mellitus and its management

Table 3 Selected human studies showing the effect of diet, gut biotics, faecal transplantation and bariatric surgery on gut microbiome and the role of gut microbiota in diabetes mellitus management

Intervention	Organism	Health benefit	Change in microbiome	Ref.
Probiotics	Human	Decreased fasting blood glucose and HbA1c levels. Increased HDL levels, however no significant effect on BMI and LDL levels were found		Kocsis et al[112], 2020
Artificial sweeteners (aspartame and acesulfame-K)	Human		Compared to controls, aspartame and acesulfame-K had different bacterial diversity (P < 0.01, P = 0.03 respectively), compared to controls	Frankenfeld et al[86], 2015
Probiotics, Prebiotics, or synbiotics	Human (meta-analysis)	The use of probiotics, prebiotics, or synbiotics showed a decrease in FBG (P < 0.01), total cholesterol (P = 0.02), triacylglycerols (P = 0.01) and insulinaemia (P < 0.01), as well as increased HDL-cholesterol levels (P < 0.01. Even though HbA1c reduction is seen it is not statistically significant. No effect on LDL-cholesterol was seen		Bock et al[115], 2020
Laparoscopic sleeve gastrectomy	Human	Decreased weight and BMI. Restored insulin tolerance and type 2 DM remission	Increased: Bacteroidetes/Firmicutes ratio at 1- and 3-months post surgery. Lactobacillales	Kikuchi et al[128], 2018;Li et al[129], 2013
Roux-en-Y gastric bypass	Human	Type 2 DM remission and improved BMI and weight loss. Improved gastric emptying and bile acid metabolism	Decreased: Bacteroidetes/Firmicutes ratio. Improved probiotic supplementation effects due to lowered pH environment	Selber-Hnatiw et al[52], 2020; Li et al[129], 2013

BMI: Body mass index; HbA1c: Hemoglobin A1c; FBG: Fasting blood glucose; HDL: High-density lipoprotein; LDL: Low-density lipoprotein.