Long-term consumption of a green/roasted coffee blend positively affects glucose metabolism and insulin resistance in humans

Protective health effects of coffee could have a widespread impact on public health considering the high intake of this beverage in industrialized countries. However, certain of coffee's health effects are contradictory such as those on type 2 diabetes mellitus (T2DM). Green coffee is richer in antioxidant phenols than roasted coffee, and thus it is likely to be a healthier option. This work evaluated the effects of long-term consumption of green coffee consumption, blended with roasted beans to improve palatability, on different glucose homeostasis markers as T2DM risk factors. A, randomized, controlled, crossover study was performed in 52 healthy men and women who consumed three servings/day of the green/roasted (35:65) coffee blend for 8 weeks during the intervention in comparison with not consuming coffee in the control stage. At the beginning and end of the coffee and control interventions, blood samples were collected, body weight measured, and dietary records and physical activity questionnaires completed. After the coffee intervention, fasting glucose levels and HOMA-IR values were significantly lower, whereas QUICKI values were higher showing improved insulin sensitivity. Fasting glucagon levels decreased, which may be associated with the increase in the glucagon-like peptide-1 (GLP-1), whereas C-peptide, glucose-dependent insulinotropic polypeptide (GIP), insulin, and HOMA-β were not affected. In conclusion, regularly consuming the green/roasted coffee blend may be recommended to prevent T2DM and reduce cardiovascular risk.This work was funded by the Spanish Ministry of Science and Innovation (projects AGL2010-18269 and Consolider-Ingenio CSD2007-00063). S.M.-L. thanks the Spanish National Research Council for her predoctoral fellowship under the JAE-Pre program funded by the European Social Fund (JAE-Pre 097. BOE 17-12-2008).Peer Reviewe