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/m2, after which insulin and the IGFs no longer stimulate glucose transport.