Measurement of glucose turnover under non-steady-state conditions has proven problematic. When the mass of the glucose pool is not changing (i.e., glucose concentrations are constant) non-steady-state error can be minimized if all glucose entering the circulation has the same specific activity as plasma [radioactive infused glucose (hot-GINF) method]. Alternatively, a second tracer can be used to measure the effective volume of glucose [variable-pV method of Issekutz (T. Issekutz, R. Issekutz, and D. Elahi. (Can. J. Physiol. 52: 215-224, 1974)]. To determine whether these techniques provide concordant assessments of insulin action under non-steady-state conditions, glucose turnover was measured in six subjects. After initiation of insulin (0.6 mU · kg-1 · min-1), both methods indicated similar rates of suppression of hepatic glucose release, which was complete by ~100- 120 min. In contrast, the traditional fixed-pV method of Steele (R. Steele, J. Wall, R. DeBodo, and N. Altszuler. Am. J. Physiol. 187: 15-24 1956) underestimated turnover (P <0.01) resulting in apparent complete suppression of glucose release within ~40 min (P <0.01 vs. other methods). The hot- GINF and variable-pV methods also yielded similar estimates of turnover after discontinuation of insulin. Both indicated that resumption of hepatic glucose release was slower (P <0.01) and fall of glucose uptake faster (P <0.01) than suggested by the fixed-pV method. Thus both the hot-GINF and variable- pV methods avoid non-steady-state error introduced by the fixed-pV method and provide concordant assessments of the rate of onset and offset of insulin action.
|Journal||American Journal of Physiology - Endocrinology and Metabolism|
|Issue number||4 27-4|
|Publication status||Published - 1993|
- glucose turnover
- hepatic glucose release
- non-steady-state error
ASJC Scopus subject areas