Comparative analysis of the efficacies of probiotic supplementation and glucose-lowering drugs for the treatment of type 2 diabetes: A systematic review and meta-analysis.

Frontiers in nutrition. 2022;9:825897
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Type 2 diabetes (T2D) is a serious medical condition often requiring antidiabetic drug management. Although commonly used antidiabetic drugs effectively control glucose levels, their tolerability profiles differ, causing various side effects. Probiotics can be used as single or multi strains to reduce glycaemic and lipid indicators and avoid the negative effects of antidiabetic medications. The study included twenty-five randomised controlled trials, of which fourteen studies assessed the effectiveness of probiotics (single probiotics, multi-strain probiotics, and probiotics with co-supplements), and eleven studies included different antidiabetic drugs such as Thiazolidinedione (TZD), Glucagon-like peptide-1 receptor agonists (GLP-1 RA), Dipeptidyl peptidase IV inhibitors (DPP-4i), and Sodium-glucose co-transporter 2 inhibitors (SGLT-2i). This systematic review and meta-analysis compared the effectiveness of probiotic and antidiabetic drugs on glycaemia, lipid profile and blood pressure in T2D patients. Probiotics were less effective than specific antidiabetic drugs in reducing fasting blood sugar levels (FBS), HbA1c levels, and triglycerides. Different probiotic formulations were effective in reducing the HOMA-IR index, total cholesterol (TC), triglycerides (TG), and systolic and diastolic pressure (SBP and DBP). A subgroup analysis showed a greater reduction in FBS, HbA1c, TC, TG, and SBP in obese and elderly participants, those who participated for a longer duration, and those from Eastern origins. Considering the high heterogeneity in baseline study characteristics among the studies included in this systematic review and meta-analysis, further studies are required to evaluate the effects of probiotics and antidiabetic drugs. However, healthcare professionals can use the study to understand the effect of probiotics and antidiabetic drugs in reducing glycaemic, lipid and hypertension profiles.


The aim of this systematic review and meta-analysis was to evaluate the effects of probiotics and glucose-lowering drugs (thiazolidinedione [TZD], glucagon-like pep-tide-1 receptor agonists [GLP-1 RA], dipeptidyl peptidase IV inhibitors, and sodium glucose co-transporter 2 inhibitors [SGLT-2i]) in patients with type 2 diabetes from randomized con-trolled trials (RCTs). The PubMed, Web of science, Embase, and Cochrane Library databases were searched on the treatment effects of probiotics and glucose-lowering drugs on glycemia, lipids, and blood pressure metabolism published between Jan 2015 and April 2021. We performed meta-analyses using the random-effects model. We included 25 RCTs (2,843 participants). Overall, GLP-1RA, SGLT-2i, and TZD significantly reduce fasting blood sugar (FBS) and glycated hemoglobin (HbA1c), whereas GLP-1 RA increased the risk of hypoglycaemia. Multispecies probiotics decrease FBS, total cholesterol (TC), and systolic and diastolic blood pressure (SBP, DBP). Moreover, subgroup analyses indicated that participants aged >55 years, BMI ≥30 kg/m2, longer duration of intervention, and subjects from Eastern countries, showed significantly higher reduction in FBS and HbA1c, TC, TG and SBP. This meta-analysis revealed that including multiple probiotic rather than glucose-lowering drugs might be more beneficial regarding T2D prevention who suffering from simultaneously hyperglycemia, hypercholesterolemia, and hypertension.

Expert Review

Conflicts of interest: None

Take Home Message:
  • Glucose-lowering drugs, except for DPP-4i, reduced FBS and HbA1c more than probiotics; and SGLT-2i induced the greatest decrease in HbA1c
  • A BMI ≥ 30 kg/m2 showed a significant decrease in FBS and the HOMA-IR index compared with those with lower BMI
  • Weight loss induced by glucose-lowering drugs and probiotic supplementation plays an important role in glycaemic control in obese patients with type 2 diabetes.

Evidence Category:
  • X A: Meta-analyses, position-stands, randomized-controlled trials (RCTs)
  • B: Systematic reviews including RCTs of limited number
  • C: Non-randomized trials, observational studies, narrative reviews
  • D: Case-reports, evidence-based clinical findings
  • E: Opinion piece, other

Summary Review:

This meta-analysis compared the effects of probiotics and glucose-lowering drugs thiazolidinedione [TZD], glucagon-like pep-tide-1 receptor agonists [GLP-1 RA], dipeptidyl peptidase IV inhibitors, and sodium glucose co-transporter 2 inhibitors [SGLT-2i]) on various outcome measures in patients with type 2 diabetes (T2D).


A search was performed on PubMed, Web of science, Embase, and Cochrane Library between January 2015 - April 2021.


25 randomised controlled trials (RCT) were included (2843 participants). 14 RCTs (842 participants) involved the administration of single probiotics, multi-strain probiotics, and probiotics with co-supplements, and 11 RCTs (2001 participants) involved TZD, GLP-1 RA, SGLT-2i, and DPP-4i. Participants in 7 of the studies had T2D, aged ≤ 55 years old. 8 RCTs included participants with a mean BMI ≥ 30 kg/m2, and 11 RCTs participants had a mean BMI < 30 kg/m2.

Effects of probiotics:

  • Fasting Blood Sugar (FBS): A reduction (−1.42, −0.32 mg/dL, p=0.000)
  • Glycated hemaglobin (HbA1c): No reduction (p = 0.000)
  • Insulin Resistance (HOMA-IR): A decrease (−0.64, −0.31; p = 0.780), regardless of probiotic strain or with a co-supplement
  • Insulin: Not significant (p = 0.000). Subgroup analysis: no reduction
  • Total Cholesterol (TC): No difference (p = 0.941). Subgroup analysis: reduction from multi-species probiotics (−0.36, −0.01 mg/dL, p = 0.871)
  • Triglycerides: Difference (−0.25 mg/dL, p = 0.958)
  • LDL-C: No changes (p = 0.189)
  • HDL-C: No increase (p = 0.014)
  • Systolic Blood Pressure (SBP): A decrease (−6.44, −0.08 mmHg, p = 0.044)
  • Diastolic Blood Pressure (DBP): A reduction (−4.53, −0.80 mmHg, p = 0.206).

Effects of glucose-lowering drugs:

  • FBS: A decrease (−4.22 mg/dL, −1.24 mg/dL, p = 0.000)
  • HbA1c: A decrease (−2.51%, −0.52%, p = 0.000) with TZD, GLP-1 RA, SGLT-2i, and DPP- 4i; a reduction with SGLT-2i (p = 0.003)
  • TC: No difference (p = 0.000). Subgroup: no decrease with single species probiotics and probiotics with co-supplements, TZD, GLP-1 RA, and DPP-4i)
  • TG: No difference (p = 0.000)
  • . HDL-C: No increase (p = 0.000). Subgroup: a decrease with TZDs (−2.37, −0.72 mg/dL). No difference with probiotic strains, or probiotics with co-supplements, GLP-1 RA, and DPP-4i
  • LDL-C: No changes (p = 0.000), Subgroups: no difference with probiotic strains, probiotics with co-supplements, TZD, GLP-1 RA, and DPP-4i).


Limited number of studies for TZD and SGLT-2i, making results potentially unreliable.


Multi species probiotics are worth considering as an adjunct to glucose-lowering drugs, and for improving lipid profiles and hypertension.

Clinical practice applications:
  • Probiotic supplementation reduced the HOMA-IR index
  • Multi-species probiotics were associated with reduction in TC and TG levels
  • DPP-4i only decreased TG levels
  • TZD was associated with decrease in HDL-C, whereas probiotic supplementation was associated with higher decrease in SBP and DBP and that GLP-1 RA increases the risk of hypoglycaemia.

Considerations for future research:
  • Semaglutide was associated with an increased risk for hypoglycaemia compared with a placebo, indicating that the safety of semaglutide needs further study
  • Dietary and physical activity should be considered in future studies
  • Heterogeneity in some indicators may be due to differences in study baseline characteristics,Larger trials needed to support the results of this meta-analysis.

Lifestyle medicine

Fundamental Clinical Imbalances : Hormonal ; Digestive, absorptive and microbiological
Environmental Inputs : Diet ; Microorganisms
Personal Lifestyle Factors : Nutrition
Functional Laboratory Testing : Blood
Bioactive Substances : Probiotics ; Antidiabetic drugs

Methodological quality

Jadad score : Not applicable
Allocation concealment : Not applicable
Publication Type : Systematic Review