The adipose tissue lipolytic response to spontaneous, non-experimental hypoglycaemic
episodes was investigated in patients with IDDM during ordinary life conditions. The
absolute concentration of glucose and glycerol in subcutaneous adipose tissue was
monitored in mobile patients with microdialysis in 16 IDDM subjects. The absolute
glycerol level in adipose tissue was about five times as high as in venous plasma,
whereas the glucose concentration was almost the same in the two compartments. Fourteen
hypoglycaemic episodes (glucose < 3.5 mmol/l) were recorded. Adipose tissue glycerol
increased markedly by 75% in response to hypoglycaemia and remained increased during
at least 4 hours following glucose nadir (F = 3.70, p = 0.003). The circulating levels
of free fatty acids increased about three-fold in parallel to the in situ lipolytic response (F = 2.98, p = 0.025). The same lipolytic response was observed
whether or not the hypoglycaemic event was perceived by the patient. A rapid decrease
in glucose concentration above hypoglycaemic levels did not affect the adipose tissue
dialysate glycerol. It is concluded that spontaneous hypoglycaemia elicits a long-term
lipolytic response in adipose tissue as evidenced by increased levels of glycerol
in adipose tissue with a parallel increase in serum free fatty acids. However, lipolysis
is not activated by a rapid glucose decrease per se. The microdialysis method can be used to characterise the lipolytic response to hypoglycaemic
episodes in every day life of IDDM patients.
Key words
Lipolysis - Free fatty acids - Glycerol - Insulin - Microdialysis
