Article

Hypoglycemia unawareness in IDDM.

Department of Medicine, University of Pittsburgh School of Medicine, Pennsylvania.
Diabetes Care (impact factor: 8.09). 12/1994; 17(12):1397-403. pp.1397-403
Source: PubMed

ABSTRACT To assess the characteristics of patients with hypoglycemia unawareness (development of neuroglycopenia without appropriate prior autonomic warning symptoms) and its predisposing factors.
We studied 43 insulin-dependent diabetes mellitus patients who were objectively categorized as having or not having hypoglycemia using the stepped hypoglycemic clamp technique in which plasma glucose was clamped at plateaus of 4.3, 3.6, 3.0, and 2.3 mmol/l and a statistical criterion (onset of autonomic warning symptoms at a plasma glucose concentration 2 SD below normal) and examined their clinical characteristics and hormonal, symptomatic, and cognitive responses.
Eleven (26%) of the patients were classified as having hypoglycemia unawareness. Compared with the other patients, unaware patients had a lower HbA1c level (P < 0.01), a longer duration of diabetes (P < 0.01), and a history of more severe hypoglycemia (P < 0.003). During experimental hypoglycemia, counterregulatory hormone responses, neuroglycopenic symptoms, and cognitive dysfunction all began at lower plasma glucose concentrations in unaware patients (P < 0.01, 0.03, and 0.01, respectively). Moreover, although the magnitudes of their plasma catecholamine responses and autonomic symptoms were reduced (both, P < 0.01), the plasma catecholamine levels at which autonomic symptoms began was not altered. Finally, as seen from glucose infusion rates necessary to maintain identical plasma glucose levels, patients with hypoglycemia unawareness had increased sensitivity to insulin (P < 0.001).
Our results confirm an association between hypoglycemia unawareness and duration of diabetes, glycemic control, and occurrence of severe hypoglycemia, and in addition provide evidence that both autonomic and neuroglycopenic symptoms are affected and that insulin sensitivity is increased, but beta-adrenergic sensitivity is not diminished.

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Keywords

43 insulin-dependent diabetes mellitus patients
 
autonomic warning symptoms
 
beta-adrenergic sensitivity
 
cognitive dysfunction
 
counterregulatory hormone responses
 
experimental hypoglycemia
 
glucose infusion rates necessary
 
hypoglycemia unawareness
 
identical plasma glucose levels
 
insulin sensitivity
 
lower HbA1c level
 
lower plasma glucose concentrations
 
plasma catecholamine levels
 
plasma catecholamine responses
 
plasma glucose
 
plasma glucose concentration 2 SD
 
severe hypoglycemia
 
statistical criterion
 
stepped hypoglycemic clamp technique
 
unaware patients