"The health benefits of coffee have been attributed to the presence of phenolic compounds including antioxidants. Studies suggest that certain dietary polyphenols have biological effects in the small intestine that can alter the pattern of glucose uptake. Roasting of coffee at high temperatures produces a number of unique compounds, which can alter the blood glucose levels and may also be involved in the regulation of satiety and insulin secretion. Coffee may also have prebiotic-like properties, altering the gut flora and ultimately digestion. It has been suggested that a novel function of some dietary phenols in humans may be to attenuate intestinal glucose absorption rates and shift the site of glucose absorption to more distal parts of the intestine."
Omani coffee has least impact on glycemic responses | Oman Observe