Can insulin be degraded in blood and ECF which become a reason for its decreased effectiveness? How do abnormal levels of HBA1c effect oxygen levels and results thereof?

Insulin is degraded specifically by an enzyme system utilizing insulin degrading enzyme and nonspecifically, by nonspecific proteases in the blood and extracellular fluid compartment. This is not usually why a person does not have effective therapy from their insulin. I would make sure that the insulin has not degraded from sun exposure, heat exposure, or is outdated. Additionally, I would be concerned that the insulin might be injected into an area of lipodystrophy that blocks the absorption of the insulin.

The HbA1c is naturally occurring. High levels are still relatively small. Therefore, it makes it unlikely that the presence of 7% or 10% HbA1c decrease oxygen in the blood or the passing of oxygen across the pulmonary capillary surface. There might be issues of poor control associated with underlying cardiovascular disease that may need to be addressed clinically.

JTL