Hypoglycemic thresholds for cognitive dysfunction in IDDM

Diabetes. 1992 Mar;41(3):392-9. doi: 10.2337/diab.41.3.392.

Abstract

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.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Blood Glucose / metabolism
  • Cognition*
  • Diabetes Mellitus, Type 1 / blood
  • Diabetes Mellitus, Type 1 / physiopathology*
  • Diabetes Mellitus, Type 1 / psychology
  • Epinephrine / blood
  • Glucagon / blood
  • Glucose Clamp Technique
  • Glycated Hemoglobin / analysis
  • Growth Hormone / blood
  • Humans
  • Hydrocortisone / blood
  • Hypoglycemia / physiopathology*
  • Insulin / blood
  • Reaction Time
  • Reference Values
  • Self Care

Substances

  • Blood Glucose
  • Glycated Hemoglobin A
  • Insulin
  • Growth Hormone
  • Glucagon
  • Hydrocortisone
  • Epinephrine