OBJECTIVE To test the hypothesis that impaired counterregulatory hormone response and symptom perception, induced by recurrent hypoglycemic episodes over 2 days, may be improved by short-term (2-day) avoidance of hypoglycemia. RESEARCH AND DESIGN: We examined two groups of insulin-dependent diabetes mellitus (IDDM) patients (n = 16), none of whom exhibited signs of peripheral or autonomic neuropathy. Two sequential euglycemic-hypoglycemic clamp studies were performed applying stable glycemic plateaus of 5.6, 3.3, 2.2, and 1.7 mmol/l, at which the patients' awareness of and responses to hypoglycemia were evaluated. In the intervention group (n = 11), three short-term hypoglycemic ( < 2.2 mmol/l) episodes (days 1-3) preceded the first clamp study (day 4), whereas the second clamp study (day 6) followed a 2-day interval of strict avoidance of hypoglycemia. A control group (n = 5) was introduced to detect adaptation effects caused by the study procedure per se. RESULTS This short-term avoidance of hypoglycemia caused improvement of the impaired counterregulatory hormone response during insulin-induced hypoglycemia involving adrenaline (P < 0.05), adrenocorticotrophic hormone (P < 0.03), and cortisol (P < 0.05). Improvement of hypoglycemia symptom awareness encompassed overall symptom perception (multiple analysis of variance, P < 0.04) and the automatic symptoms of heart pounding (P < 0.05) and sweating (P < 0.05). CONCLUSIONS The previously reported compromised neuroendocrine counterregulation and symptom awareness, occurring as a consequence of repetitive hypoglycemic episodes over 2 days, may be improved by a single 2-day interval of strict avoidance of hypoglycemia