Detection of hypoglycaemia by microdialysis measurements of glucose in subcutaneous adipose tissue.

The aim of the present investigation was to study how various fractional sampling times affect the detection of hypoglycaemia, using microdialysis of the adipose tissue. We therefore studied eight healthy subjects during a standardized hyperinsulinaemic hypoglycaemic clamp. The glucose concentration in the adipose tissue dialysate was determined in timed fractions of 15 min, 30 min and 60 min and compared to those in arterialized venous plasma. Before and after hypoglycaemia, the plasma and adipose tissue glucose concentrations were similar. However, during hypoglycaemia, the adipose tissue glucose nadir, as measured in 15-min fractions of the tissue dialysate, was significantly lower than that in plasma (2.1 +/- 0.1 vs. 2.4 +/- 0.1 mmol/l, p = 0.05) and during the increase in plasma glucose, the corresponding increase in adipose tissue glucose was delayed by approximately 20 min (p = 0.004). When the microdialysate was sampled over 30 or 60 min periods, there was a close agreement between the plasma and adipose tissue glucose nadirs. We conclude that there is a protracted fall in subcutaneous adipose tissue glucose levels in response to insulin-induced hypoglycaemia. While shorter microdialysis sampling periods improve the resolution of the hypoglycaemic event, 30-min fractions seem sufficient to detect hypoglycaemia in a clinically relevant way.