Endocrine Abstracts

Hyperinsulinemia leading to insulin resistance is the major factor in the pathogenesis of type 2 diabetes mellitus. And also defect in glucose uptake is among the primary defects associated with peripheral insulin resistance. Interestingly, the result from our previous study indicated that the ethanolic extract of Combretum decandrum Roxb. (CD) had a hypoglycemic effect in type 1 diabetic rat model. Therefore this study examined the effect of CD extract on the glucose tolerance and glucose uptake of hyperinsulinemic rats. The long acting insulin at 2 IU/kgBW was injected subcutaneously three times daily into male Wistar rats for 15 consecutive days to induce hyperinsulinemic situation. The oral glucose tolerance test (OGTT) was performed on the day before and 3 days after the administration of ethanolic extract of CD. Four hyperinsulinemic rats were anesthetized with pentobarbital then the epididymal fat pads were removed. The amount of glucose uptaken into these fat cells was detected by using 2-deoxy-D-(U-C¹⁴) glucose as a probe. We found that the percent increase in blood glucose of hyperinsulinemic rats, at 120 min. after oral administration of glucose 3 g/kg BW, was significantly (P<0.05) higher than that of normal rats (42.45±5.60 and 3.04±5.77% respectively). After receiving CD extract at doses of 0.5 and 0.75 g/kgBW, the percent increases in blood glucose of hyperinsulinemic rats were significantly lower than before treatment (2.86±9.77 and 24.86±5.90% respectively). In the glucose uptake investigation, it was found that the CD at concentrations of 14.2 and 42.8 μg/ml significantly increased the basal glucose transport into the hyperinsulinemic rat’s adipocytes (1450.39±222.16 and 1637.70±246.79 dpm respectively, as compared to control of 713.28±134.46 dpm). In conclusions, the CD extract at doses of 0.5 and 0.75 g/kgBW can improve the glucose tolerance of hyperinsulinemic rats. The OGTT improvement effect may be mediated through the enhancement of the cellular glucose transport.