Insulin induced hypoglycaemia: comparison of glucose and glycerol concentrations in plasma and microdialysate from subcutaneous adipose tissue.

AIMS To investigate the dynamics between plasma and dialysate glucose during hypoglycaemia in children. STUDY DESIGN Six children in prepuberty or early puberty were investigated by multiple blood sampling and microdialysis of subcutaneous adipose tissue during a standard arginine-insulin tolerance test. Glucose and glycerol, as an index of lipolysis, were measured in samples from both compartments. Plasma concentrations of insulin and the main counterregulatory hormones were also measured. RESULTS Plasma and dialysate glucose concentrations were very similar at baseline and increased in concert after infusion of arginine, probably in response to glucagon release. After insulin injection, glucose in both plasma and dialysate fell in parallel. The subsequent hypoglycaemic stress response induced a rapid rebound in the plasma concentration with a mean (SD) delay in the dialysate of 16 (3) minutes. Plasma glycerol was approximately fivefold lower than in the dialysate and did not fluctuate significantly. Dialysate glycerol decreased with arginine infusion and reached a nadir immediately following insulin administration. Subsequently, the antilipolytic effect of insulin was overcome by the hypoglycaemic stress response, and lipolysis prevailed in spite of hyperinsulinaemia. CONCLUSION After rapidly induced hypoglycaemia, rebound of interstitial glucose concentrations is significantly delayed compared with plasma concentrations, and the antilipolytic effect of hyperinsulinaemia is opposed possibly by the hypoglycaemic stress response.