Delayed glucose response in the rat model: More evidence that a high protein diet alters glucose kinetics

Abstract

Based on previous findings that the insulin response to a 2 hour oral glucose tolerance test (OGTT) was altered in rats fed a high protein diet (Sanchez et al. 2006), the purpose of this study was to determine the effects of a high protein diet on glucose kinetics by extending the OGTT beyond 2 hours. Eight Sprague Dawley rats were fed a high protein (HP) diet (65% protein, 35% fat) and seven rats consumed a standard chow (SC) diet for seven weeks. Blood was collected by tail bleeding at 0, 15, 30, 60, 120, 150, and 180 minutes after dosing with a 2 g/kg of 50% dextrose solution. Glucose tolerance was impaired by the high protein diet (SC = 16113 ± 460 mg/dl/180 min; HP = 17728 ± 254 mg/dl/180 min; p < 0.05) as reflected by the area under the glucose concentration curve. In contras, the area under the insulin concentration curve was not effected by the high protein diet (SC = 108.48 ± 15.44 ng/ml/180 min; HP = 87.99 ± 10.96 ng/ml/180 min). Peak glucose response was delayed in the high protein diet group (SC = 30 minutes at 105 ± 2 mg/dl; HP = 60 minutes at 114 ± 4 mg/dl). Body mass was significantly greater in the control group from the initial to final weighing (SC = 253 ± 4 g to 283 ± 5 g; HP = 245 ± 4 g to 258 ± 4 g; p < 0.05) and hemoglobin A1C was significantly lower in the high protein diet group (SC = 3.4 ± 0.1 %; HP = 3.1 ± 0.1 %; p < 0.05). These findings suggest that a high protein diet alters glucose kinetics as evidenced by an increased area under the glucose concentration curve and a decrease in hemoglobin A1C. This research was partially funded through a grant issued by the GPSA at the University of Nevada, Las Vegas.