Elevated fasting concentrations of α-hydroxybutyrate (from threonine and methionine), β-hydroxyisobutyrate (catabolite of valine) and α-ketoglutarate (produced from glutamate by alanine aminotransferase and aspartate aminotransferase) have been linked to impaired glucose tolerance and insulin resistance [9–11]. The gene discussed is GPT; the disease is Impaired glucose tolerance.