Elevated circulating levels of branched-chain amino acids have been associated with insulin resistance where decreased degradation of branched-chain amino acids could be what is leading to elevated circulating levels of branched-chain amino acids.
Methylcrotonyl CoA carboxylase and propionyl-CoA carboxylase are two biotin-dependent enzymes in the branched-chain amino acid degradation pathway. Dysregulation of the sodium-dependent multivitamin transporter which transports biotin could dysregulate the branched-chain amino acid degradation pathway leading to high levels of circulating branched-chain amino acids and insulin resistance.
Insulin resistance is present in 52% of individuals with bipolar disorder. Insulin resistance develops is brains of individuals with Alzheimer’s disease. In China in individuals with schizophrenia the prevalence of insulin resistance is 37.2% Both disease processes and drugs used to treat these illnesses could increase insulin resistance in theses illnesses. A commonality among these illnesses could be dysregulation of the sodium-dependent multivitamin transporter both by disease processes and drugs used to treat these illnesses.
The sodium-dependent multivitamin transporter transports both biotin and pantothenate. Pantothenate is needed to synthesize coenzyme A which is closely tied to the actions of biotin-dependent enzymes. Biotinylation of the sodium-dependent transporter reduces transport by the sodium-dependent multivitamin transporter. High levels of biotin could decrease transport of pantothenate by the sodium-dependent multivitamin transporter. A combination of pantothenic acid and biotin where 500 mg. of pantothenic acid is taken once a day away from supplemental biotin and 5 mg of biotin is taken three times a day could word work better in controlling hyperglycemia than biotin alone.
Only the abundance of biotinylated 3-methylcrotonyl-CoA carboxylase (holo-MCC) and propionyl-CoA carboxylase (holo-PCC) can distinguish between biotin-deficient and biotin-sufficient individuals. Methylcrotonyl CoA carboxylase and propionyl-CoA carboxylase could be particularly sensitive to biotin deficiencies.