PCBD1 and diabetes mellitus: In summary, the available literature on diabetes research using routine NBS results has shown that (1) future type 1 diabetes patients have lower acylcarnitines when compared to controls, (2) gestational diabetes exerts some influence on infant metabolism manifesting as higher carnitine and acylcarnitine fractions on NBS as compared to unexposed infants and (3) higher phenylalanine levels on routine NBS results are seen in patients with PCBD1 mutations (some of whom were diagnosed with type 2 diabetes later in life).