Myocardial and whole-body
glucose metabolism was assessed in
19 insulin-dependent diabetes mellitus (
IDDM) patients. A hyperglycemic clamp was performed 1) in the absence of
insulin at
free fatty acid (FFA) levels of 1.0 mmol/l (test 1); 2) in the absence of
insulin at low FFA levels (0.1 mmol/l) by means of a
lipid-lowering
drug,
acipimox (test 2); 3) during
insulin infusion to achieve systemic levels of 400 pmol/l and 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
intralipid infusion (test 4). Myocardial
glucose uptake was measured by positron emission tomography (PET) and 2-[18F]fluoro-
2-deoxy-D-glucose. Whole-body
glucose uptake was measured in the four conditions by the
glucose infusion rate during the PET scanning period. Myocardial
glucose uptakes were 40.3 +/- 18.0, 395.5 +/- 139.6, 852.2 +/- 99.1, and 1,388.4 +/- 199.1 mumol.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, and 30.5 +/- 5.6 mumol.kg body wt-1.min-1 during tests 1, 2, 3, and 4, respectively. Thus, in
IDDM patients without
coronary artery disease under the condition of
hyperglycemia, an increase of myocardial
glucose uptake was obtained either by lowering of FFA levels during hypoinsulinemia or by an increase in FFA levels during
hyperinsulinemia. In both conditions no significant changes of whole-body
glucose uptake were demonstrated.