Antidiabetic and Metabolic Effects of Turmeric (Curcuma Longa) in Patients with Type 2 Diabetes Mellitus or Hyperglycemia – A Systematic Meta-Review and Meta-Analysis

Abstract

Background: Curcumin, the primary bioactive compound in turmeric (Curcuma longa Linn.), has demonstrated potential benefits in managing type 2 diabetes mellitus (T2DM) and hyperglycemia. This systematic meta-review aimed to evaluate the effectiveness of turmeric in improving glycemic control, lipid profiles, and other metabolic markers in the patients with T2DM or hyperglycemia.

Methods: A comprehensive literature search was conducted across seven electronic databases to identify relevant studies published up to December 2023. Inclusion criteria focused on randomized controlled trials included in systematic reviews or meta-analyses assessing curcumin’s effects on metabolic markers. Data were extracted systematically, and the methodological quality of included reviews was assessed using AMSTAR-2. Meta-analyses were performed using STATA 17 to synthesize outcomes for fasting blood glucose (FBG), glycated hemoglobin (HbA1c), lipid profiles, and other markers, employing random-effects models to account for heterogeneity.

Results: Thirteen systematic reviews and meta-analyses of 63 unique randomized controlled trials involving 3706 human participants met the inclusion criteria. The pooled analysis revealed that curcumin significantly reduced FBG (mean difference [MD] = - 6.30 mg/dL; 95% CI: - 9.33, - 3.27), HbA1c (MD = - 0.31%; 95% CI: - 0.57, - 0.05), low - density lipoprotein (LDL) cholesterol (MD = - 5.95 mg/dL; 95% CI: - 9.43, - 2.47), and triglycerides (TG) (MD =  -12.88 mg/dL; 95% CI: - 20.09, - 5.67) while increasing high-density lipoprotein (HDL) cholesterol (MD = 1.46 mg/dL; 95% CI: 0.37, 2.56). No significant effects were observed on total cholesterol, blood pressure, body mass index, blood urea nitrogen, or creatinine levels. Heterogeneity across studies was high but consistent with meta-analytical expectations for diverse populations and interventions.

Conclusions: Curcumin supplementation shows statistically significant improvements in glycemic control and lipid profiles in individuals with T2DM or hyperglycemia, supporting its potential as an adjunct therapy. However, its effects on renal markers, blood pressure, and body weight remain inconclusive. Moreover the efficacy of the crude powder of turmeric remain unexplored. Future trials should address long-term efficacy and safety to optimize the therapeutic role of curcumin and turmeric powder in diabetes management.