KEYSTONE, COLO. — Hypoglycemia unawareness is a common problem constituting a major risk factor for severe hypoglycemic episodes involving seizures or coma, Georgeanna Klingensmith, M.D., said at a conference on management of diabetes in youth sponsored by the University of Colorado.
Moreover, hypoglycemia unawareness is likely to become even more frequent as physicians strive to meet tighter glycosylated hemoglobin targets in order to reduce the long-term risks of diabetic retinopathy and nephropathy, predicted Dr. Klingensmith, professor of pediatrics at the university.
The good news is, hypoglycemia unawareness is reversible simply by avoidance of hypoglycemia for 7–21 days.
“I usually find that 7–10 days after setting target blood glucose levels higher, the patient can regain hypoglycemia awareness. Then you can reset the blood glucose targets. So if we can correct hypoglycemia unawareness, we may be able to avoid hypoglycemia in the first place,” she explained.
Before you can set about reversing hypoglycemia unawareness, however, you first have to suspect its presence. That's why it's vital to ask type 1 diabetic patients about hypoglycemic symptoms at every office visit.
“I'm kind of a nut case on this, because I think hypoglycemia unawareness is more common than we expect and really is a cause of severe hypoglycemia,” she added.
Symptoms of neuroglycopenia suggest a patient is experiencing hypoglycemia unawareness. So do hypoglycemic symptoms occurring at a blood glucose level of less than 60 mg/dL.
Hypoglycemia unawareness results from CNS adaptation to hypoglycemia, which increases levels of the glucose transport protein GLUT1 mRNA in the ventromedial hypothalamus. The result is preferential brain glucose uptake. The brain doesn't; sense hypoglycemia is occurring, hence, it no longer releases epinephrine as a counterregulatory response.
Nocturnal hypoglycemia is a major cause of hypoglycemia unawareness. In one representative study in which 47 children with type 1 diabetes underwent continuous blood glucose monitoring for a mean of 70 hours, 83% experienced at least one episode of unrecognized nocturnal hypoglycemia.