Diabetologia

, Volume 38, Issue 12, pp 1412–1418

Lack of preservation of higher brain function during hypoglycaemia in patients with intensively-treated IDDM

  • A. Maran
  • J. Lomas
  • I. A. Macdonald
  • S. A. Amiel
Originals

DOI: 10.1007/BF00400601

Cite this article as:
Maran, A., Lomas, J., Macdonald, I.A. et al. Diabetologia (1995) 38: 1412. doi:10.1007/BF00400601

Summary

Severe hypoglycaemia with cognitive dysfunction is 3 times more common in intensively, rather than conventionally, treated insulin-dependent diabetes mellitus (IDDM). To investigate the effect of diabetes control on higher brain function during acute hypoglycaemia, we studied one of the earliest detectable changes in cognitive function, i.e. the four-choice reaction time, and symptomatic and hormonal responses during euglycaemic and hypoglycaemic clamping in human subjects. There were no changes in symptoms or counterregulatory hormones and four-choice reaction time was stable during 220 min of euglycaemic insulin clamping in five men with IDDM, with a coefficient of variation of less than 2.2% (1% for accuracy) for the cognitive function test. During stepped hypoglycaemic clamping however, hormonal responses and subjective awareness of hypoglycaemia occurred in all groups but started at much lower blood glucose concentrations in eight intensively-treated diabetic subjects (Group 1) than in ten conventionally-treated (Group 2) or in eight non-diabetic subjects (Group 3). For example, for adrenaline, plasma glucose thresholds were 2.7±0.2 vs 3.4±0.2 and 3.2±0.1 mmol/l, respectively, p<0.05, Group 1 vs Groups 2 or 3 and for subjective awareness of hypoglycaemia 2.3±0.2 vs 3.0±0.1 and 3.2±0.1 mmol/l, p ≤ 0.003), as in previous studies. In contrast, deterioration in reaction time occurred at 3.2±0.3, 3.2±0.2 and 3.0+0.2 mmol/l, respectively (p=NS), thus occurring at higher glucose levels than subjective awareness in the intensively-treated subjects only. The altered hierarchy of responses to hypoglycaemia in well-controlled intensively-treated diabetes explains the increased risk of severe hypoglycaemia without warning seen in such patients.

Key words

Choice reaction time cognitive function hypoglycaemia counterregulation diabetes mellitus 

Abbreviations

IDDM

Insulin-dependent diabetes mellitus

Copyright information

© Springer-Verlag 1995

Authors and Affiliations

  • A. Maran
    • 1
  • J. Lomas
    • 1
  • I. A. Macdonald
    • 2
  • S. A. Amiel
    • 1
  1. 1.Unit for Metabolic MedicineUnited Medical and Dental Schools of Guy's and St Thomas' HospitalsLondonUK
  2. 2.Department of Physiology and Pharmacology, Queen's Medical CentreNottingham UniversityNottinghamUK
  3. 3.Department of MedicineKing's College School of Medicine and DentistryLondonUK

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