A randomized study conducted on patients with metabolic syndrome and just published in British Journal Nutrition 2018, showed that the supplementation, within a balanced dietary regimen, of decaffeinated green coffee bean extract capsules (800 mg per day for 8 weeks) is able to reduce fasting blood glucose, systemic blood pressure, insulin resistance, abdominal obesity and appetite.

Hanieh Roshan et al., Effects of green coffee extract supplementation on anthropometric indices, glycaemic control, blood pressure, lipid profile, insulin resistance and appetite in patients with the metabolic syndrome: a randomised clinical trial.  British journal of nutrition 2018.