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English: Figure 2. Diagnostic flow chart for beta-ketothiolase (T2) deficiency. An FFA/TKB cutoff of 0.3 is not an absolute value. Fasting for too long may decrease the ratio, and glucose infusion reduces FFA faster than TKB, also decreasing the ratio. Dotted lines indicate rare but possible consequences. Extreme hyperglycemia with elevated HbA1c is usually diagnosed as diabetic ketoacidosis; however, ketoacidosis mimicking diabetic ketoacidosis has been reported in some organic acidemias. Hence, although HbA1c is a good marker for diabetic ketoacidosis, normal HbA1c levels cannot exclude diabetic ketoacidosis conclusively (indicated by a dotted line). If the urinary organic acid profile is nonspecific during ketoacidosis, T2 and SCOT should be analyzed by enzyme assay or gene analysis, since patients with T2 deficiency could have a nonspecific urinary organic acid profile (indicated by a dotted line). FFA/TKB indicates free fatty acids/total ketone body; HbA1c, glycated hemoglobin; MCT1, monocarboxylate transporter 1; MHBD, 2-methyl-3-hydroxybutyryl-CoA dehydrogenase; SCOT, succinyl-CoA:3-oxoacid CoA transferase; T2, mitochondrial acetoacetyl-CoA thiolase.