Drinking coffee appears to lower markers for subclinical inflammation and raise HDL cholesterol levels but does not affect glucose metabolism, a small study has found. The study included 47 habitual coffee drinkers who stopped drinking coffee for one month. The following month, they drank four cups of filtered coffee per day, followed by eight cups of filtered coffee daily in the third month. The participants were otherwise in good health, less than 65 years of age but had an increased risk of diabetes based on a diabetes risk score. The results showed that after two months drinking coffee there were significant decreases in markers of subclinical inflammation, including interleukin-18 and adiponectin, but no increases in levels of C-reactive protein. Total cholesterol levels increased by 12% after the second month of drinking coffee, but there was also a 7% increase in HDL-cholesterol levels.