Hypoglycemia -- What Every Person on Insulin
Should Know
posted 02/16/04
by Ben Eastman
What is Hypoglycemia?
All people with diabetes, regardless of type or their method
of treatment, suffer from high blood glucose levels (hyperglycemia) when left
untreated.
The treatment of diabetes, whether pills or insulin, can lead
to hypoglycemia.
Hypoglycemia is the term used to describe a low blood glucose
level (BG). This would be a blood glucose level of less than 65 mg/dl.
Consequences of Hypoglycemia
A severe hypoglycemic event has a number of consequences. Some
are well understood, others are surrounded by controversy.
Hypoglycemia can result in accident and injury. Other times it
can be so severe it can be fatal. Repeated episodes of hypoglycemia appear to
affect a person's ability to recognize the warning signs of approaching attacks
in the future. Some researchers have even claimed to have found evidence that
hypoglycemia may affect brain function.
Death
Some research estimates that between four and 13 percent of
the deaths of people with type 1 diabetes are the result of hypoglycemic events.
"What's worrisome about these deaths is that they are due to
the treatment," says Philip Cryer, MD, FACP past- president of the American
Diabetes Association (ADA).
One especially frightening possibility for people on insulin
that may be the result of severe hypoglycemia is what the journal Diabetic
Medicine referred to in 1991 as "dead in bed syndrome." Victims of the
syndrome are found dead in an undisturbed bed, observed to have been in good
health the day before and are free from evidence of late diabetes complications.
Some of the strongest recent evidence in support of adverse
effects of hypoglycemia on the brain comes from an article in the June 1997
issue of Diabetes Care. Using magnetic resonance imaging (MRI)
researchers found that cortical (brain) atrophy was present in 45 percent of
type 1 test subjects with a history of recurrent severe hypoglycemia. Cortical
atrophy was nonexistent in type 1 subjects without such a history.
Regardless of the association between hypoglycemia and brain
function, the researchers also found that these abnormal MRIs were far more
prevalent in type 1s than in the nondiabetic population of comparable age (35 to
52 years old). The abnormalities discovered are normally associated with aging
and are extremely rare in subjects of this age. The data suggest that they may
"be a feature of diabetes and may represent accelerated brain aging associated
with the metabolic disorder," they claim.
It should be noted that very little is known about the
consequences of hypoglycemia on children. Boyle points out that no subjects of
the DCCT were under 14-years-old. Many researchers agree that the consequences
of hypoglycemia could be much worse for children, however, because their brains
are still developing.
Hypoglycemic Unawareness
A major disadvantage of repeated hypoglycemia is its effect on
hypoglycemic awareness. A study from the journal Diabetes found that
the enhanced rates of cerebral blood flow found at the onset of hypoglycemia are
associated with a diminished perception of low blood glucose levels and
weakening of the hormonal counter-regulatory response.
Generally, more severe hypoglycemic events equal more
hypoglycemic unawareness. This can be remedied however.
According to Cryer, three separate studies have shown that
hypoglycemic unawareness is "largely, if not entirely, the result of multiple
hypoglycemic reactions." Two of these three studies also showed that as little
as two to three weeks of "scrupulous avoidance of hypoglycemia will reverse
hypoglycemic unawareness," says Cryer.
What Can Be Done?
A study by Bruce Bode, MD, published in 1996 in Diabetes
Care suggests that pump therapy can greatly reduce the incidence of severe
hypoglycemia. The study documents a more than six-fold decline in the incidence
of severe hypoglycemia during the first year of pump therapy. The rate remained
significantly lower in the three year follow up as well.
DCCT researcher Patrick Boyle, MD, mentions that two clinical
studies have also shown that severe hypoglycemia can be reduced by more frequent
BG testing.
"The majority of hypoglycemic events observed in the DCCT
occurred at night. For that reason, patients should check their BG levels before
bed and not go to sleep unless their BGs are in a good, safe range," adds Linda
"Freddi" Fredrickson, MA, CDE, RN.
Source: Diabetes Interview.
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