Insulin is activated in response to an influx of dietary amino acids and glucose into the blood.
Insulin facilitates the uptake of glucose and amino acids into the liver (and muscles).
In the liver, glucose is stored as glycogen, and glutathione is made of methionine/cysteine, glutamic acid and glycine.
Thus insulin increases GSH levels. Full Free Article
Therefore, in diabetes (lower insulin), the level of glutathione (GSH) is significantly lower, which compromises your defense capacity against radicals.
Insulin also stimulates the transportation of liver-GSH to peripheral tissues.
Due to a lack of the uptake of the GHS precursors into the liver, they remain in the blood. Cystein is readily hydrolized.
Due to a lack of glycogen, which results in low blood sugar levels, these GSH percursors may be converted into energy instead of GSH.
In diabetes, the levels of these precursors is very low.
When GSH levels are very low, insulin compensates for this by stimulating the production of another powerful anti-oxidant: NADPH
Insulin does so by stimulating Glucose 6-Phosphate Dehydrogenase activity. Full Free article