Suppression of body weight gain preserves acute insulin response to glucose in the portal vein of spontaneously type 2 diabetic rats with visceral obesity.

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.