Hypoglycemic thresholds for cognitive dysfunction in IDDM.
Fourteen poorly controlled insulin-dependent diabetes mellitus (IDDM) patients (HbA1c 11 +/- 0.5%) with a mean +/- SE duration of disease of 15 +/- 2 yr were studied to evaluate the hypoglycemic threshold for cognitive dysfunction under insulin-induced hypoglycemia. The P300 event-related potential, a measure of cognitive function, and reaction time (RT) in response to visual stimuli under euglycemic conditions and at plasma glucose concentrations of 3.5 and 2.5 mM (63 and 45 mg/dl, respectively) during a constant insulin infusion were recorded. Baseline P300 latency was similar to that of a nondiabetic control group, but baseline RT was greater in the IDDM group. There was no increase in P300 latency or RT under euglycemic clamp conditions or at a plasma glucose level of 3.5 mM (63 mg/dl). However, when plasma glucose was lowered to 2.5 mM (45 mg/dl), there was an increase in P300 latency and a prolongation of RT. As plasma glucose returned to baseline, P300 latency and RT remained prolonged. After administration of intravenous glucose and a meal, P300 latency and RT returned to baseline. P140, an event-related potential reflecting sensory processes, was not altered. Because P300 latency changes paralleled RT changes, hypoglycemia appears to slow decision-making processes in IDDM. This study revealed that 1) baseline P300 latency is not elevated in poorly controlled IDDM patients, suggesting no cumulative cognitive dysfunction.
Blackman
J D
JD
Department of Medicine, University of Chicago, Illinois 60637.
Towle
V L
VL
Sturis
J
J
Lewis
G F
GF
Spire
J P
JP
Polonsky
K S
KS
D001786:Blood Glucose / Q000378:metabolism; D003071:Cognition; D003922:Diabetes Mellitus, Type 1 / Q000097:blood / Q000503:physiopathology* / Q000523:psychology; D004837:Epinephrine / Q000097:blood; D005934:Glucagon / Q000097:blood; D015309:Glucose Clamp Technique; D006442:Glycated Hemoglobin / Q000032:analysis; D013006:Growth Hormone / Q000097:blood; D006801:Humans; D006854:Hydrocortisone / Q000097:blood; D007003:Hypoglycemia / Q000503:physiopathology*; D007328:Insulin / Q000097:blood; D011930:Reaction Time; D012016:Reference Values; D012648:Self Care
D001786:Blood Glucose; D004837:Epinephrine; D005934:Glucagon; D006442:Glycated Hemoglobin; D013006:Growth Hormone; D006854:Hydrocortisone; D007328:Insulin