CYP2D6 and hyperinsulinemic hypoglycemia, familial, 4: There was no statistically significant difference in the mean absolute haemoglobin reduction and mean relative percentage haemoglobin reduction between individuals with reduced and normal CYP2D6 enzyme activity, or between those with G6PD deficiency and G6PD normal or heterozygous females on days 1, 2, 3, and 7.