PROLONGED BUT PARTIAL IMPAIRMENT OF THE HYPOGLYCEMIC PHYSIOLOGICAL-RESPONSE FOLLOWING SHORT-TERM HYPOGLYCEMIA IN NORMAL SUBJECTS

Recent studies have reported reduced endocrine and symptomatic respons es 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 non -diabetic subjects aged 23-35 years in the week following antecedent h ypoglycaemia. Blood glucose levels were held at plateaus of 5 mmol/l a nd 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 o f 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 wee k) 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 day s) 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, th e total symptom score response to hypoglycaemia was attenuated on Day 3 (p < 0.03) but not Day 8 (p = 0.10). Autonomic symptoms were similar ly 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.