MYOCARDIAL GLUCOSE-UPTAKE EVALUATED BY POSITRON EMISSION TOMOGRAPHY AND FLUORODEOXYGLUCOSE DURING HYPERGLYCEMIC CLAMP IN IDDM PATIENTS - ROLE OF FREE FATTY-ACID AND INSULIN LEVELS

Myocardial and whole-body glucose metabolism was assessed in 19 insuli n-dependent diabetes mellitus (IDDM) patients, A hyperglycemic clamp w as performed 1) in the absence of insulin at free fatty acid (FFA) lev els of 1.0 mmol/l (test 1); d) in the absence of insulin at low FFA le vels (0.1 mmol/l) by means of a lipid-lowering drug acipimox (test 2); 3) during insulin infusion to achieve systemic revels of 400 pmol/l a nd FFA levels of 0.1 mmol/l (test 3); and 4) at the insulin levels of test 3 but increasing FFA to 1.0 mmol/l by means of heparin and intral ipid infusion (test 4). Myocardial glucose uptake was measured by posi tron emission tomography (PET) and 2-[F-18]fluoro-2-deoxy-D-glucose. W hole-body glucose uptake was measured In the four conditions by the gl ucose infusion rate during the PET scanning period, Myocardial glucose uptakes were 40.3 +/- 18.0, 395.5 +/- 139.6, 852.2 +/- 99.1, and 1,38 8.4 +/- 199.1 mu mol . kg tissue(-1) . min(-1) (mean +/- SD) and whole -body glucose uptakes were 10.1 +/- 2.3, 10.1 +/- 3.4, 42,8 +/- 5.8, a nd 30.5 +/- 5.6 mu mol . kg body body wt(-1) . min(-1) during tests 1, 2, 3, and 4, respectively, Thus, in IDDM patients without coronary ar tery disease under the condition of hyperglycemia, an increase of myoc ardial glucose uptake was obtained either by lowering of FFA levers du ring hypoinsulinemia or by an increase in FFA levels during hyperinsul inemia. In both condit;ions no significant changes of whole-body gluco se uptake mere demonstrated.