RESPONSES OF INSULIN TO ORAL GLUCOSE AND FRUCTOSE LOADS IN MARGINALLYCOPPER-DEFICIENT RATS FED STARCH OR FRUCTOSE

The purpose of this study was to assess the effects of dietary fructos e either alone or in combination with marginal copper deficiency in we anling male rats exposed to their respective diets for only 2 wk. This short duration of exposure to inadequate copper intake prevents progr essive morbidity brought about by increasing periods of exposure to di etary copper deprivation. Weanling male rats were fed a copper-deficie nt (0.6 mu g Cu/g) or a copper-adequate (6.0 mu g Cu/g) diet containin g 62% fructose or 62% starch for 2 wk. Either an oral glucose or an or al fructose tolerance test was conducted after an overnight fast. Insu lin levels were elevated by either oral glucose or oral fructose at fa sting and at 30 min postload in rats fed fructose compared with those fed starch. Despite high levels of plasma, insulin blood glucose was n ot reduced. Marginal copper deficiency had no effect on either plasma insulin or blood glucose. Data identify fructose as the sole agent res ponsible for inducing adverse changes in glucose metabolism Two weeks of fructose consumption was sufficient to produce these changes.