Cognitive performance, symptoms and counter-regulation during hypoglycaemia in patients with type 1 diabetes and high or low renin-angiotensin system activity.
BACKGROUND
High basal renin-angiotensin system (RAS) activity is associated with increased risk of severe hypoglycaemia in type 1 diabetes. We tested whether this might be explained by more pronounced cognitive dysfunction during hypoglycaemia in patients with high RAS activity than in patients with low RAS activity.


METHODS
Nine patients with type 1 diabetes and high and nine with low RAS activity were subjected to hypoglycaemia and euglycaemia in a cross-over study using an intravenous insulin infusion protocol. Cognitive function, electroencephalography, auditory evoked potentials and hypoglycaemic symptoms were recorded.


RESULTS
At a hypoglycaemic nadir of 2.2 (SD 0.3) mmol/L the high RAS group displayed significant deterioration in cognitive performance during hypoglycaemia in the three most complex reaction time tasks. In the low RAS group, hypoglycaemia led to cognitive dysfunction in only one reaction time task. The high RAS group reported lower symptom scores during hypoglycaemia than the low RAS group, suggesting poorer hypoglycaemia awareness.


CONCLUSIONS
High RAS activity is associated with increased cognitive dysfunction and blunted symptoms during mild hypoglycaemia compared to low RAS activity. This may explain why high RAS activity is a risk factor for severe hypoglycaemia in type 1 diabetes.
Høi-Hansen
Thomas
T
Endocrinology Section, Department of Cardiology and Endocrinology, Hillerød Hospital, Hillerød, Denmark.
Pedersen-Bjergaard
Ulrik
U
Andersen
Rikke Due
RD
Kristensen
Peter Lommer
PL
Thomsen
Carsten
C
Kjaer
Troels
T
Høgenhaven
Hans
H
Smed
Annelise
A
Holst
Jens Juul
JJ
Dela
Flemming
F
Boomsma
Frans
F
Thorsteinsson
Birger
B
D000328:Adult; D001786:Blood Glucose / Q000378:metabolism; D003071:Cognition / Q000502:physiology; D003922:Diabetes Mellitus, Type 1 / Q000150:complications / Q000503:physiopathology* / Q000523:psychology*; D004569:Electroencephalography / Q000187:drug effects; D005072:Evoked Potentials, Auditory / Q000187:drug effects; D005260:Female; D006801:Humans; D007003:Hypoglycemia / Q000209:etiology / Q000503:physiopathology*; D007328:Insulin / Q000097:blood; D008297:Male; D008875:Middle Aged; D011597:Psychomotor Performance / Q000502:physiology; D012084:Renin-Angiotensin System / Q000502:physiology*
D001786:Blood Glucose; D007328:Insulin