Cinnamon bark (Cinnamomum verum or Cinnamomum cassia) has been the subject of growing scientific interest for its potential role in supporting or treating metabolic syndrome, a cluster of conditions that increase the risk of heart disease, stroke, and type 2 diabetes. Several clinical studies and meta-analyses have investigated cinnamon's effects on blood glucose, lipid profiles, and markers of insulin sensitivity. Some randomized controlled trials have reported modest reductions in fasting blood glucose and improvements in insulin sensitivity in people with type 2 diabetes or metabolic syndrome taking cinnamon supplements (typically 1–6 grams daily), although results are not completely consistent across studies. A 2019 meta-analysis published in the journal Clinical Nutrition found that cinnamon supplementation significantly reduced fasting plasma glucose and improved lipid parameters (total cholesterol, LDL, triglycerides) in patients with metabolic syndrome and related conditions.

The proposed mechanisms include cinnamon's polyphenolic compounds, which may enhance insulin signaling and have antioxidant effects. However, the magnitude of benefit is generally modest, and quality of evidence is limited by small sample sizes, short study durations, and heterogeneity among trials. Most major health organizations do not currently endorse cinnamon as a primary therapy for metabolic syndrome, but acknowledge its potential as a safe adjunct to standard care. In summary, while cinnamon bark is traditionally used for a variety of ailments, there is also moderate scientific evidence supporting its adjunctive use in metabolic syndrome, but it should not replace conventional lifestyle and pharmacologic interventions.