Prolonged but partial impairment of the hypoglycaemic physiological response following short-term hypoglycaemia in normal subjects

Recent studies have reported reduced endocrine and symptomatic responses to hypoglycaemia 18–24 h after antecedent hypoglycaemia in both non-diabetic subjects and those with insulin-dependent diabetes mellitus. We examined these and peripheral physiological responses in eight nondiabetic subjects aged 23–35 years in the week following antecedent hypoglycaemia. Blood glucose levels were held at plateaus of 5 mmol/l and 2.5 mmol/l for 30 min during hyperinsulinaemic (60 mU · m−2 · min−1) morning clamps on days 1, 3 and 8 of two study periods separated by at least 4 weeks. Measurements were made at time 0, 15 and 30 min of each plateau on each day. On the afternoon of Day 1 we also induced either euglycaemia with a blood glucose level of 5 mmol/l (control week) or hypoglycaemia of 2.9 mmol/l (hypo week) for 2 h in random order. The adrenaline response to morning hypoglycaemia (p<0.01 on all days) was attenuated on Day 3 (p<0.05) and Day 8 (p<0.05) compared to Day 1 of hypo week only. Sweating was also attenuated on Day 3 (p<0.05) and Day 8 (p<0.02) of hypo week only. Noradrenaline levels and tremor increased during hypoglycaemia on each study day (p<0.05) but did not differ between days in either week. During hypo week only, the total symptom score response to hypoglycaemia was attenuated on Day 3 (p<0.03) but not Day 8 (p=0.10). Autonomic symptoms were similarly affected. In summary, the physiological responses to hypoglycaemia are affected differentially by antecedent hypoglycaemia with sweating and adrenaline responses remaining impaired for at least 5 days.