PGM1 and hyperinsulinemic hypoglycemia, familial, 4: Most patients with phosphoglucomutase 1 deficiency (PGM1-CDG) develop hypoglycaemia, which seems to be because of multifactorial: hyperinsulinism, inappropriate counter-regulatory hormonal response (low cortisol), impaired glucose release from glycogen during fasting and malnutrition (82).