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Unawareness of hypoglycemia by insulin-dependent diabetics
A Grimaldi1, F Bosquet, P Davidoff
1Service Diabétologie, C. H. U. Pitie-Salpetriere, Paris, France.
Abstract:
After several years of insulin therapy, about 20% of insulin-dependent diabetics have little or no perception of hypoglycaemia because of a loss of the adrenergic warning symptoms. This defect, poorly correlated with the presence of autonomic neuropathy, has been classically explained by a defect in the catecholamine secretion. We compared the hormonal counterregulation during hypoglycaemia induced by subcutaneous injection of insulin in 7 insulin-dependent diabetics with poor perception of hypoglycaemia and experiencing repeated episodes of severe hypoglycaemia (group A) and 7 insulin-treated diabetics with very good perception of hypoglycaemia and not experiencing severe hypoglycaemia (group B). Groups A and B were similar in terms of age, duration of diabetes, HbA1c level and degenerative complications. The glucagon levels were identical and non-reactive in the two groups. The basal levels and secretion peaks of adrenaline, noradrenaline, growth hormone and cortisol were similar between the two groups, but there was a significant delay in secretion in group A with a blood glucose threshold of adrenergic secretion of between 3.1 +/- 0.5 and 1.6 +/- 0.2 mmoles/l in group A and between 4.6 +/- 0.3 and 3.2 +/- 0.2 mmoles/l in group B (P less than 0.05). This delayed secretion could be explained by desensitisation of the hypothalamic glucostat and could be due to the frequency and/or severity of hypoglycaemic episodes.
Insights
Diabetics with poor hypoglycemia awareness show delayed hormonal responses. This suggests frequent severe hypoglycemia may desensitize the brain
Area of Science:
- Endocrinology
- Metabolic Disorders
- Neuroscience
Background:
- Approximately 20% of insulin-dependent diabetics lose awareness of hypoglycemia due to diminished adrenergic warning symptoms.
- This phenomenon is often attributed to impaired catecholamine secretion, independent of autonomic neuropathy.
- Understanding the mechanisms behind impaired hypoglycemia perception is crucial for managing diabetes effectively.
Purpose of the Study:
- To compare hormonal counterregulation during induced hypoglycemia in insulin-dependent diabetics with and without hypoglycemia unawareness.
- To investigate the relationship between the frequency/severity of hypoglycemia and the delay in hormonal responses.
- To explore potential mechanisms, such as hypothalamic glucostat desensitization, underlying impaired hypoglycemia perception.
Main Methods:
- Insulin-induced hypoglycemia was administered to two groups of 7 insulin-dependent diabetics: one with poor hypoglycemia perception (Group A) and one with good perception (Group B).
- Hormonal responses (glucagon, adrenaline, noradrenaline, growth hormone, cortisol) were measured.
- Groups were matched for age, diabetes duration, HbA1c, and complications.
Main Results:
- Glucagon levels were non-reactive and identical in both groups.
- Basal levels and secretion peaks of adrenaline, noradrenaline, growth hormone, and cortisol were similar between groups.
- A significant delay in the secretion of these counterregulatory hormones was observed in Group A (poor perception) compared to Group B (good perception), with a lower blood glucose threshold for adrenergic response.
Conclusions:
- The delay in counterregulatory hormone secretion in diabetics with impaired hypoglycemia awareness suggests a desensitization of the hypothalamic glucostat.
- This desensitization may be a consequence of frequent or severe episodes of hypoglycemia.
- These findings highlight the importance of preventing recurrent hypoglycemia to maintain adequate counterregulatory responses and hypoglycemia awareness.