EFFECTS OF HYPERGLYCEMIA ON IN-VIVO ADIPOSE-TISSUE METABOLISM STUDIEDWITH MICRODIALYSIS IN IDDM SUBJECTS

The effect of hyperglycemia on in vivo adipose tissue metabolism was s tudied with microdialysis in seven lean patients with insulin-dependen t diabetes mellitus (IDDM) receiving a constant infusion of insulin (3 6 pmol . m(-2) . min(-1)). Glucose was infused in a randomized fashion to maintain either a lower glucose level (6.6 +/- 0.3 mM, mean +/- SE ) or hyperglycemia (11.8 +/- 0.8 mM) for 3 h. For insulin concentratio ns of 84 +/- 12 and 96 +/- 12 pM, hyperglycemia (11.8 +/- 0.8 mM) did not alter the plasma glycerol or lactate levels significantly but resu lted in a significant (P < 0.0001) increase in plasma and free fatty a cid levels (0.49 +/- 0.13 vs. 0.32 +/- 0.08 mM). Plasma catecholamine levels were unchanged during hyperglycemia. Interstitial glycerol conc entrations, measured in abdominal subcutaneous adipose tissue as an in dex of lipolysis, were not significantly influenced by hyperglycemia w hen compared with concentrations at the lower glucose level (92 +/- 30 vs. 106 +/- 18 mu M) Moreover, hyperglycemia did not change abdominal adipose interstitial lactate levels significantly (1,248 +/- 174 vs. 1,351 +/- 159 mu M during euglycemia). It may be concluded that hyperg lycemia has no independent antilipolytic effect in IDDM subjects. Furt hermore, in these patients, hyperglycemia gives no further lactate pro duction in the subcutaneous adipose tissue in the presence of low phys iological insulin levels.