PRESERVATION OF PHYSIOLOGICAL CELL RESPONSES TO HYPOGLYCEMIA 2 DAYS AFTER ANTECEDENT HYPOGLYCEMIA IN PATIENTS WITH IDDM

OBJECTIVE - To assess the effects of short-term antecedent hypoglycemi a on responses to further hypoglycemia 2 days later in patients with I DDM. RESEARCH DESIGN AND METHODS - We studied eight type I diabetic pa tients without hypoglycemia unawareness or autonomic neuropathy during two periods at least 4 weeks apart. On day 1, 2 h of either clamped h yperinsulinemic (60 mU . m(-2) . min(-1)) hypoglycemia at 2.8 mmol/l o r 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 physiolo gical responses were measured every 10-20 min. RESULTS - When compared with the responses measured following euglycemia, the responses of no repinephrine 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 epinep hrine (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 (p eak, 194 +/- 34 vs. 179 +/- 47 g(-1) . m(-2) . h(-1) [P = 0.73]; thres hold, 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 +/- 0.1 mmol/l glucose [P = 0.1 5]), 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. C ONCLUSIONS - The effect on hypoglycemic physiological responses of 2 h of experimental hypoglycemia lasts for 1-2 days in these patients wit h IDDM. The pathophysiological effect of antecedent hypoglycemia may b e of shorter duration in IDDM patients, compared with nondiabetic subj ects.