Diabetes Care, Vol 20, Issue 8 1293-1298, Copyright © 1997 by American Diabetes Association
Preservation of physiological responses to hypoglycemia 2 days after antecedent hypoglycemia in patients with IDDM
E George, JL Marques, ND Harris, IA Macdonald, CA Hardisty and SR Heller
Academic Division of Medicine, University of Sheffield, U.K.
OBJECTIVE: To assess the effects of short-term antecedent hypoglycemia on
responses to further hypoglycemia 2 days later in patients with IDDM.
RESEARCH DESIGN AND METHODS: We studied eight type I diabetic patients
without hypoglycemia unawareness or autonomic neuropathy during two periods
at least 4 weeks apart. On day 1, 2 h of either clamped hyperinsulinemic
(60 mU.m-2.min-1) hypoglycemia at 2.8 mmol/l or euglycemia at 5.0 mmol/l
were induced. Hyperinsulinemic hypoglycemia was induced 2 days later with
40 min glucose steps of 5.0, 4.0, 3.5, 3.0, and 2.5 mmol/l. Catecholamine
levels and symptomatic and physiological responses were measured every
10-20 min. RESULTS: When compared with the responses measured following
euglycemia, the responses of norepinephrine 2 days after hypoglycemia were
reduced (peak, 1.4 +/- 0.4 [mean +/- SE] vs.1.0 +/- 0.3 nmol/l [P <
0.05]; threshold, 3.4 +/- 0.1 vs. 2.9 +/- 0.1 mmol/l glucose [P <
0.01]). The responses of epinephrine (peak, 4.0 +/- 1.4 vs. 3.5 +/- 0.8
nmol/l [P = 0.84]; threshold, 3.8 +/- 0.1 vs. 3.6 +/- 0.1 mmol/l glucose [P
= 0.38]), water loss (peak, 194 +/- 34 vs. 179 +/- 47 g-1.m-2.h-1 [P =
0.73]; threshold, 2.9 +/- 0.2 vs. 2.9 +/- 0.2 mmol/l glucose [P = 0.90]),
tremor (peak, 0.28 +/- 0.05 vs. 0.37 +/- 0.06 root mean square volts (RMS
V) [P = 0.19]; threshold, 3.2 +/- 0.2 vs. 3.1 +/- 0.2 mmol/l glucose [P =
0.70]), total symptom scores (peak, 10.6 +/- 2.1 vs. 10.8 +/- 1.9 [P =
0.95]; threshold, 3.3 +/- 0.2 vs. 3.6 +/0 0.1 mmol/l glucose [P = 0.15]),
and cognitive function (four-choice reaction time: threshold, 2.9 +/- 0.2
vs. 3.0 +/- 0.2 mmol/l glucose [P = 0.69]) were unaffected. CONCLUSIONS:
The effect on hypoglycemic physiological responses of 2 h of experimental
hypoglycemia lasts for 1-2 days in these patients with IDDM . The
pathophysiological effect of antecedent hypoglycemia may be of shorter
duration in IDDM patients, compared with nondiabetic subjects.