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- Title
Effect of antecedent hypoglycemia on cognitive function and on glycemic thresholds for counterregulatory hormone secretion in healthy humans.
- Authors
Mellman, Michael J.; Davis, Maris R.; Brisman, Michelle; Shamoon, Harry; Mellman, M J; Davis, M R; Brisman, M; Shamoon, H
- Abstract
<bold>Objective: </bold>To determine whether reduced hormonal, symptomatic, and/or cognitive responses to hypoglycemia are caused by an increase in the plasma glucose concentration required to stimulate these counterregulatory parameters after antecedent hypoglycemia.<bold>Research Design and Methods: </bold>We studied nine healthy volunteers during stepped hypoglycemia clamps (plasma glucose targets from 80 to 50 mg/dl in 10 mg/dl steps) on two separate days. The study was preceded either by a 2-h period of hypoglycemia (plasma glucose 58 +/- 2 mg/dl) or a 2-h period of euglycemia (plasma glucose 94 +/- 2 mg/dl) for 90 min.<bold>Results: </bold>The plasma glucose that triggered secretion of plasma norepinephrine (NE) was lower after antecedent hypoglycemia (control = 74 +/- 2 and experimental = 67 +/- 2 mg/dl, respectively, P < 0.005). In contrast, a relatively higher plasma glucose stimulated secretion of other counterregulatory hormones after antecedent hypoglycemia: growth hormone (GH) (65 +/- 2 to 72 +/- 2 mg/dl, P < 0.01); glucagon (63 +/- 2 to 70 +/- 2 mg/dl, P < 0.01); and epinephrine (EPI) (68 +/- 2 to 76 +/- 2 mg/dl, P < 0.01) when comparing control days with experimental days. Hypoglycemic symptoms were first observed at a plasma glucose plateau of 59 +/- 2 mg/dl. Motor function reflected by Digit Symbol Substitution deteriorated equally whether there had been antecedent hypoglycemia or euglycemia. Logical (immediate) memory deteriorated in the control study at a plasma glucose of 54 +/- 2 mg/dl but remained unchanged at equivalent hypoglycemia in the experimental study (P < 0.03).<bold>Conclusions: </bold>Our conclusions are as follows: 1) symptoms of moderate hypoglycemia occur at plasma glucose levels averaging approximately 5-15 mg/dl lower than the plasma glucose concentrations required to trigger counterregulatory hormone release; 2) after acute antecedent hypoglycemia, glucagon, EPI, and GH secretion occur at higher plasma glucose concentrations and NE is released at lower plasma glucose concentrations; and 3) there may be CNS adaptation to prior hypoglycemia reflected in preservation of logical memory function at plasma glucose levels of approximately 50 mg/dl. These findings suggest that thresholds for hormone secretion and for changes in cognitive function can be altered very acutely by foregoing hypoglycemia in healthy humans.
- Publication
Diabetes Care, 1994, Vol 17, Issue 3, p183
- ISSN
0149-5992
- Publication type
journal article
- DOI
10.2337/diacare.17.3.183