Arginine vasopressin response to insulin-induced hypoglycemia in insulin-dependent diabetics with asymptomatic hypoglycemia.

Insulin-induced hypoglycemia causes an increase in plasma vasopressin (AVP) in healthy subjects but the response in diabetics is not established. We investigated the effect of insulin-induced hypoglycemia on ten insulin-dependent diabetics with asymptomatic hypoglycemia, and compared the results with those for seven healthy subjects. The lack of adrenergic symptoms of hypoglycemia in insulin dependent diabetics being attributed to a diminished beta-adrenergic sensitivity, the effect of isoprenaline infusion was investigated as control. Insulin-induced hypoglycemia resulted in both populations in significant increase (P less than 0.01) in AVP in addition to significant increases in heart rate, plasma epinephrine (E), norepenephrine (NE) and cortisol (COR). Effective osmolality and mean arterial blood pressure did not vary. Diabetics showed smaller increase in AVP (P less than 0.01) and heart rate (P less than 0.05) than controls. Maximal E, NE and COR values did not differ between the two populations. Isoprenaline infusion resulted in increase in heart rate and plasma renin activity, but AVP and COR did not vary in the two populations. In conclusion, insulin-induced hypoglycemia released AVP in diabetics with asymptomatic hypoglycemia, but the response was weaker than in healthy subjects. A causal hypothalamic alteration of beta-adrenergic or glycopenia sensitivity is discussed.