Short-term low carbohydrate/high-fat diet intake increases postprandial plasma glucose and glucagon-like peptide-1 levels during an oral glucose tolerance test in healthy men

Background/Objectives:Postprandial hyperglycemia increases the risks of development of type 2 diabetes and cardiovascular diseases. The purpose of this study was to determine whether a 3-day low-carbohydrate/high-fat diet (LC/HFD) alters postprandial plasma glucose and incretin levels during oral glucose tolerance test (OGTT) in healthy men.Subjects/Methods:Nine healthy young men (age (means.e.), 271 years; body mass index, 221 kg/m 2) consumed either a normal diet (ND: energy from 22% fat) or a LC/HFD (energy from 69% fat) for 3 days each. The total energy intake from each diet was similar. An OGTT was performed after each 3-day dietary intervention. Postprandial plasma glucose, insulin, free fatty acid and glucagon-like peptide-1 (GLP-1) levels were determined at rest and during the OGTT.Results:Plasma glucose levels and incremental area under the curve during the OGTT were significantly higher in the LC/HFD trial than in the ND trial (P0.024). In addition, increase in GLP-1 levels was significantly higher in the LC/HFD trial than in the ND trial (P0.025). The first-phase insulin secretion indexes were significantly lower in the LC/HFD trial than in the ND trial (P0.041).Conclusions:These results demonstrate that even short-term LC/HFD increased postprandial plasma glucose and GLP-1 levels in healthy young men. A decrease in first-phase insulin secretion may partially contribute to the short-term LC/HFD-induced increase in postprandial plasma glucose levels.