SIRT1 and gestational diabetes: Another gene of interest that showed a significant increase in expression in the GDM/SIRT1(↑) group was G6PD, encoding glucose-6-phosphate dehydrogenase (G6PD): the rate-limiting enzyme in the pentose-phosphate pathway that catalyzes the dehydrogenation reaction of glucose-6-phosphate to 6-phosphogluconolactone and reduces nicotinamide adenine dinucleotide phosphate (NADPH).