G6PD is an enzyme that helps in the breakdown of carbohydrates. If it isn't present then certain pathways that deal with glucose metabolism aren't activated. There's a lot more to it but the short form is that glucose is a bad actor and this helps keep it contained. You more than likely are deficient here. This shouldn't be a great surprise since this is the most common deficiency in humans.
G6PD deficiency: its role in the high prevalence of hypertension and diabetes mellitus
What has been found is that KPD's are far more likely to have G6PD deficiency than other diabetics. You could view it as a marker for KPD.