INSULIN-RESISTANCE CHARACTERIZES GLUCOSE-UPTAKE IN SKELETAL-MUSCLE BUT NOT IN THE HEART IN NIDDM

Skeletal muscle insulin resistance and coronary heart disease (CHD) of ten precede non-insulin-dependent diabetes mellitus (NIDDM). A recent study showed the myocardium of patients with CHD to be insulin resista nt, independent of blood flow. We determined whether myocardial insuli n resistance is a feature of NIDDM patients with no CHD. Skeletal musc le and myocardial glucose uptake were determined in 10 patients with N IDDM and 9 age- and weight-matched normal men of similar age and body mass index men using [F-18]-2-fluoro-2-deoxy-D-glucose and positron em ission tomography under normoglycaemic hyperinsulinaemic conditions. W hole body glucose uptake, as determined by the euglycaemic clamp techn ique, was significantly lower in the patients with NIDDM (35+/-3 mu mo l/kg body weight.min) than the normal subjects (45 +/- 3 mu mol/kg bod y weight.min, p < 0.02). Insulin-stimulated femoral muscle glucose upt ake was significantly lower in the patients with NIDDM (71 +/- 6 mu mo l/kg muscle.min) than in the normal subjects (96 +/- 5 mu mol/kg muscl e.min, p < 0.01). Whole body glucose uptake was correlated with femora l muscle glucose uptake in the entire group (r = 0.76, p < 0.001), in patients with NIDDM and in normal subjects. Rates of insulin-stimulate d myocardial glucose uptake were comparable between the patients with NIDDM (814+/-76 mu mol/kg muscle.min) and the normal subjects (731+/-6 3 mu mol/kg muscle.min, p>0.4). Whole body or femoral muscle, and myoc ardial glucose uptake were not correlated in all subjects, patients wi th NIDDM or normal subjects. We conclude that insulin resistance of th e myocardium is not a feature of uncomplicated NIDDM.