Effects of saffron and crocin on glycemic control: an exploratory systematic review and meta-analysis of randomized trials
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Background
Saffron and its constituent crocin have been investigated as adjuncts for metabolic dysfunction. Their effects on longer-term glycemic exposure and fasting indices may differ.
Objectives
To assess the effects of saffron and its constituents on glycated hemoglobin (HbA1c), fasting glucose, and insulin resistance.
Search methods
We searched PubMed Central on June 11, 2025, and PubMed on October 5, 2025.
Selection criteria
Randomized controlled trials in humans comparing saffron or its constituents with a control for at least four weeks and reporting a relevant glycemic outcome were eligible. Comparisons were selected to isolate the effect of saffron or crocin.
Data collection and analysis
We synthesized continuous outcomes as mean differences (MDs) with 95% confidence intervals (CIs), using inverse-variance random-effects models. HbA1c was the primary outcome. Fasting glucose and the homeostatic model assessment of insulin resistance (HOMA-IR) were secondary outcomes.
Main results
Twelve trials contributed 570 participants to the analyzed comparisons. Populations included adults with type 1 or type 2 diabetes, metabolic syndrome or coronary artery disease, and adolescents with obesity and prediabetes. Seven trials (391 participants) reported HbA1c: the pooled MD was − 0.25 percentage points (95% CI − 0.58 to 0.08; I 2 = 61%). Fasting glucose was lower with saffron or crocin across 12 trials (570 participants; MD − 16.16 mg/dL, 95% CI − 27.02 to − 5.31; I 2 = 74%). Five trials (212 participants) contributed to HOMA-IR (MD − 1.19, 95% CI − 2.25 to − 0.12; I 2 = 80%). Fixed-effect sensitivity analyses gave smaller estimates across the three outcomes.
Authors’ conclusions
Saffron and crocin were associated with lower fasting glucose and HOMA-IR, whereas the HbA1c estimate remained compatible with both a reduction and little difference. Variation in populations, preparations, and trial sizes limits interpretation of the average effects. Larger trials with standardized preparations and adequate follow-up are needed to establish the persistence and clinical relevance of these findings.
Funding
None.
Plain language summary
Saffron and crocin, a constituent of saffron, have been studied as supplements for people with metabolic conditions. We combined randomized trials that compared these interventions with a control. Twelve trials contributed data from 570 participants in the analyzed groups. Fasting glucose was lower on average in the intervention groups. An index of insulin resistance also decreased, although results varied considerably among trials. The results for HbA1c, which reflects glucose exposure over several months, did not establish a clear reduction. The trials used different preparations and included people with different metabolic conditions. These findings do not establish that saffron or crocin can replace established diabetes treatment, or that the observed changes prevent diabetes complications.
