The age-related changes in acute
insulin response after
glucose loading and the influence of suppression of
body weight gain were investigated by using blood samples from portal and peripheral veins. We placed
indwelling catheters in the portal vein of 12- and 24- wk-old Otsuka Long-Evans Tokushima fatty (OLETF) rats (n = 8, 12), and age-matched control Long-Evans Tokushima Otsuka (LETO) rats (n = 8, 6). To suppress the
body weight gain, 6 out of 12 OLETF rats were fed chow containing 50 ppm
voglibose (VOG) from 8 until 24 wk of age. After fasting for 17 h, rats underwent 1 g/kg oral
glucose tolerance test (OGTT). Peripheral
glucose levels after
glucose loading were significantly higher in 12- and 24-wk-old OLETF rats than in the age-matched LETO rats. Values for delta
insulin 15 min/delta
glucose 15 min (delta I15 min/delta G15 min) in portal blood were 0.029 +/- 0.011 and 0.009 +/- 0.009 (12 wk of age) and 0.03 +/- 0.03 and -0.01 +/- 0.01 (24 wk of age) in the LETO rats and OLETF rats. At the age of 24 wk, the
body weights in VOG-treated OLETF rats were significantly lower than those in the OLETF rats. And there was significantly greater acute
insulin response to
glucose in VOG-treated OLETF rats than in the OLETF rats. Acute
insulin response to
glucose decreased with advancing age and the suppression of
body weight gain preserved the response in spontaneously type 2 diabetic rats with visceral fat
obesity.