EFFECT OF MODERATE OBESITY ON GLUCOSE-TRANSPORT IN HUMAN MUSCLE

We have shown that maximally stimulated glucose transport is reduced in in vitro incubated muscle of morbidly obese subjects. To investigate the possibility that a ''threshold'' of obesity exists, above which glucose transport is significantly decreased, hormone (insulin, IGF-I, or IGF-II) stimulation of glucose transport was correlated with body mass index using muscle biopsies from a group of 30 lean to obese females with BMI ranging from 16 to 40. There was a significant negative relationship between stimulation for glucose transport and BMI (R= 0.765). These data suggest there is no obesity threshold for insulin resistance in skeletal muscle but a continuous decline in glucose transport below a BMI of approximately 30 kg/m(2), after which insulin and the IGFs no longer stimulate glucose transport.