INS and phenylketonuria: Fasting insulin levels, with a mean of 12.74 ± 8.4 mIU/L (range 1.8–42.5), were above upper limit in 15 PKU patients (26.3%) and 3 MHPA patients (11.54%) and were markedly higher in the former group (p = 0.035) (Table 1).