Metabolite profile deviations in an oral glucose tolerance test-a comparison between lean and obese individuals.

Objective While impaired glucose tolerance diagnosed by the oral glucose tolerance test (OGTT) is a common trait in obese individuals, less is known about changes in levels of other metabolites. The aim was to reveal the complex alterations in metabolite levels provoked by an OGTT and its perturbation in obese individuals. Methods Gas chromatography/mass spectrometry was used to profile metabolite levels in serum from 14 obese participants (body mass index [BMI] of 43.6 ± 1.5 kg m⁻² [mean ± SEM]) at 0, 30, and 120 min during a standard 2-h 75 g OGTT. Metabolite profiles from six lean individuals (BMI of 22.4 ± 2.4 kg m⁻²), collected from a previous study, were included for comparison. Results In the obese group, 59 metabolite profiles were determined. Among these, 16 deviated from profiles in the lean group. Deviating metabolites were categorized into three groups. Delayed reduction in levels of five fatty acids. Increased levels at 30 min of five amino acids, including isoleucine and leucine. A blunted increase at 30 min of six metabolites. Conclusions Metabolomics analysis revealed distinct differences in alterations of metabolite levels during an OGTT in obese and lean subjects. To this end, our data suggests a disrupted regulation of ketogenesis, lipolysis and proteolysis in obese individuals. [ABSTRACT FROM AUTHOR]