To determine if methane producers (MP) have a higher post-prandial serum acetate concentrations over a 12-hour period than methane nonproducers (MNP) in subjects with impaired glucose tolerance (IGT), we studied 19 subjects: 11 MP and 8 MNP. Breath gases, hydrogen and methane, fasting serum total and high-density lipoprotein (HDL) cholesterol and triacylglycerol were measured. Plasma glucose and insulin and serum short chain fatty acid concentrations were measured fasting and over a 12-hour period. MP had significantly greater fasting serum total cholesterol (6.5+/-0.3 vs 5.4+/-0.3 mmol/L; P = 0.01) and LDL cholesterol (4.2+/-0.3 vs 3.0+/-0.4 mmol/L; P = 0.04) concentrations than MNP. No differences in TG or HDL cholesterol concentrations were observed. The mean 5-12 hour incremental area in serum acetate in MP was significantly higher compared to MNP (299.4+/-37.2 vs 151.3+/-47.6 μmol/L; P = 0.02). From these results we can conclude that in IGT subjects, a positive methane producing status increases post-prandial serum acetate which may contribute to the increased serum total cholesterol concentration.