CONSEQUENCES OF HIGH DIETARY FRUCTOSE IN THE ISLET-TRANSPLANTED RAT WITH SUBOPTIMAL BETA-CELL MASS

Fructose (FR) feeding in rats provides a model of dietary-induced insu lin resistance that has been used to examine interactions among the cl uster of metabolic disorders including insulin resistance, hyperinsuli nemia, hypertension, and dyslipidemia known as Syndrome X. In animals with reduced beta-cell mass, however, insulin resistance may not have similar associated disorders. Therefore this study examined the conseq uences of FR feeding in rats with a reduced beta-cell mass. Formerly d iabetic islet-transplanted (TX) or sham-operated (SHAM) male Wistar Fu rth rats were fed a purified control (CNTL) diet or a diet containing either 40 or 70% (wt/wt) FR for 3-5 wk. FR feeding in SHAM animals res ulted in elevated triglyceride levels but did not affect fed or fastin g glucose and insulin concentrations, blood pressure, glucose toleranc e, and the acute insulin response to a glucose bolus compared with CNT L-fed animals. Among TX animals, hypertriglyceridemia and fasting hype rglycemia were observed only in those fed FR. Thus the effects of diet -induced insulin resistance are limited to dyslipidemia, if insulin se cretory capacity is adequate, but are detrimental to both glucose and lipid metabolism in combination with a reduced beta-cell mass.