ABSTRACT
<p><b>OBJECTIVE</b>To study the effects of early high fat diet on sugar metaboliam, insulin sensibility and pancreatic β cellularity in young rats.</p><p><b>METHODS</b>Sixty male weaned young rats were randomly fed with high fat diet (high fat group) and normal diet (control group). The body weight, viscus fattiness and fasting plasma glucose (FPG) were measured after 3, 6 and 9 weeks. Serum insulin level was measured with radioimmunoassay. The ultrastructure of pancreas was observed under an electricmicroscope.</p><p><b>RESULTS</b>The high fat group had significantly higher body weight and visceral fat weight than the control group after 3 weeks. There were no significant differences in the FPG level between the two groups at all time points. The levels of fasting insulin and HOMAIR in the high fat group were significantly higher than those in the control group after 3, 6 and 9 weeks (P<0.01). Dilation of rough endoplasmic reticulum and mild swelling of mitochondria of islet β-cells were observed in the high fat group after 6 weeks.</p><p><b>CONCLUSIONS</b>Early high fat diet may induce a reduction in insulin sensitivity and produce insulin resistance in young rats. Endoplasmic reticulum expansion in β-cells may be an early sign of β-cell damage due to obesity.</p>