Fasting blood glucose

Method

Venous plasma or serum glucose concentration by clinical enzymatic assay in a sample drawn after an overnight fast of stated duration.

The method is part of the endpoint identity. Studies measuring the same quantity by a different method are held as separate endpoints.

Notes

Glycated haemoglobin indexes the same construct over a different integration window and both improve by falling, which is exactly why they get merged. This is a single-timepoint concentration; HbA1c integrates roughly ninety days of exposure. Trials shorter than about twelve weeks move this endpoint without moving HbA1c, so a merged node manufactures a null in every short trial. Also distinct from peak postprandial glucose and from postprandial glucose area under the curve, which are challenge responses and can move in the opposite direction to the basal value. This is also one of the two INPUTS to HOMA-IR.

Findings

8 findings from 7 compounds, strongest first.

• resveratrol — no detected effect on

  AWell establishedGrade A, Well established. Replicated human trial evidence, consistent direction.FindingNull result

  “The results indicated that resveratrol did not improve FBG levels versus placebo (WMD: −3.54 mg/dL, 95% CI: −12.45, 5.38; P=0.44;.”

  Study

  meta-analysis

  Participants

  1,151

  Dose

  8.1-3000 mg/day resveratrol across the pooled trials

  Population

  Adults with type 2 diabetes; whole-population pooled estimate across all 19 RCTs, resveratrol vs placebo

  Effect -3.54 mean difference, 95% CI -12.45 to 5.38

  Effects of Resveratrol on Metabolic Indicators in Patients with Type 2 Diabetes: A Systematic Review and Meta-Analysis.2022PMID:35685602

• coenzyme Q10 — decreases

  BLikelyGrade B, Likely. Human evidence, limited replication or design limits.Finding

  “The administration of CoQ10 resulted in a significant decrease in FBG levels (ESWMD = −5.04, 95% CI: −7.67, −2.40; p < 0.001, I 2 = 58.7%, p = 0.04) (Figure.”

  Study

  meta-analysis

  Dose

  110 to 376.6 mg/day CoQ10 across the included meta-analyses

  Population

  Adults with type 2 diabetes, obesity, polycystic ovary syndrome, chronic kidney disease, metabolic syndrome and other cardiometabolic conditions, from the randomised controlled trials pooled by eight meta-analyses.

  Effect -5.04 mean difference, 95% CI -7.67 to -2.4

  Effects of Coenzyme Q10 Supplementation on Glycemic Control Biomarkers: An Umbrella Review of Meta-Analyses of Randomised Controlled Trials.2026PMID:41859772

• melatonin — decreases

  BLikelyGrade B, Likely. Human evidence, limited replication or design limits.Finding

  “The pooled analysis displayed that melatonin supplementation substantially lowered serum FBG levels in the melatonin group compared with the placebo group (WMD: −11.63 mg/dL, 95% CI: −19.16, −4.10).”

  Study

  meta-analysis

  Dose

  0.3-100 mg/day oral

  Population

  adults in 63 RCTs of melatonin supplementation vs placebo across mixed clinical populations

  Effect -11.63 mean difference, 95% CI -19.16 to -4.1

  Comprehensive Effects of Melatonin Supplementation on Cardiometabolic Risk Factors: A Systematic Review and Dose-Response Meta-Analysis.2025PMID:41515249

• magnesium(2+) — decreases

  BLikelyGrade B, Likely. Human evidence, limited replication or design limits.Finding

  “Compared with placebo, Mg supplementation reduced fasting plasma glucose in people with diabetes.”

  Study

  meta-analysis

  Population

  people with diabetes

  Oral Magnesium Supplementation for Treating Glucose Metabolism Parameters in People with or at Risk of Diabetes: A Systematic Review and Meta-Analysis of Double-Blind Randomized Controlled Trials.2021PMID:34836329

• L-glutamine — decreases

  BLikelyGrade B, Likely. Human evidence, limited replication or design limits.Finding

  “Meta-analysis showed that glutamine supplementation significantly decreased significantly serum levels of FPG [SMD: - 0.73, 95% CI - 1.35, - 0.11, I2: 84.1%] and CRP [SMD: - 0.58, 95% CI - 0.1, - 0.17, I2: 0%].”

  Study

  meta-analysis

  Population

  participants in randomized clinical trials of glutamine supplementation

  Effect of glutamine supplementation on cardiometabolic risk factors and inflammatory markers: a systematic review and meta-analysis.2021PMID:33865313

• curcumin — decreases

  BLikelyGrade B, Likely. Human evidence, limited replication or design limits.Finding

  “Twelve studies assessed reduction of FBS indicating curcumin supplementation was associated with a significant reduction in FBS, with MD (95% CI) of −2.05 (−3.08, −1.01) mg/dL, I2 = 0%, see Supplementary Appendix O.”

  Study

  meta-analysis

  Dose

  80–3000 mg/day pooled across bioavailability-enhanced forms (80–1000 mg/day), curcumin extracts (1500 mg/day) and turmeric powder (2000–3000 mg/day)

  Population

  Adults with MAFLD (NAFLD/NASH); 12 RCTs; glycaemic indices were an additional (secondary) outcome of this review, not a liver endpoint

  Effect -2.05 mean difference, 95% CI -3.08 to -1.01

  An updated meta-analysis of effects of curcumin on metabolic dysfunction-associated fatty liver disease based on available evidence from Iran and Thailand.2023PMID:37037891

• berberine — no detected effect on

  CSuggestiveGrade C, Suggestive. Weak human evidence, or strong evidence in a mismatched population.FindingNull result

  “Notably, compared with the placebo, BBR did not change fasting blood glucose (FBG), fasting insulin or fasting proinsulin C-peptide levels (Supplementary Table  2).”

  Study

  crossover

  Participants

  15

  Dose

  single oral dose of 1 g berberine tablets

  Population

  15 healthy men with normal glucose tolerance; secondary observation in a single-dose hyperglycaemic clamp trial, fasting glucose measured after an overnight fast before and after dosing

  Berberine is an insulin secretagogue targeting the KCNH6 potassium channel.2021PMID:34556670

• curcumin — no detected effect on

  CSuggestiveGrade C, Suggestive. Weak human evidence, or strong evidence in a mismatched population.FindingNull result

  “Nanocurcumin supplementation showed no significant effects on fasting blood glucose (SMD: -0.44; 95% CI: -2.16 to 1.28), HbA1c (SMD: 0.19; 95% CI: -1.26 to 1.65), or lipid profile parameters, including total cholesterol, LDL-C, HDL-C and triglycerides (all p > 0.05).”

  Study

  meta-analysis

  Participants

  389

  Population

  adults with type 2 diabetes mellitus (T2DM)

  Evaluating the Effects of Nanocurcumin Supplementation in Type 2 Diabetes Mellitus: A Systematic Review and Meta-Analysis of Randomized Controlled Trials.2026PMID:42171191