Effect of a high protein diet on glucose tolerance in the rat model

The purpose of this study was to determine the effects of a high protein diet on glucose tolerance. Nine Sprague Dawley rats received a high protein (HP) diet (65% protein, 35% fat) and eight rats consumed a standard chow (SC) diet over eight weeks. Oral glucose tolerance tests (OGTT) were performed at the end of the third and the seventh week. The diet did not effect glucose tolerance in the first (SC = 10 357 ± 294 mg/dl/120 min; HP = 9846 ± 300 mg/dl/120 min) or the second OGTT (SC = 10 134 ± 395 mg/dl/120 min; HP = 10 721 ± 438 mg/dl/120 min) as reflected by the area under the glucose concentration curve. Similarly, the area under the insulin concentration curve was not effected by the high protein diet during the first (SC = 49.21 ± 8.46 ng/ml/120 min; HP = 41.75 ± 10.54 ng/ml/120 min) or the second OGTT (SC = 96.63 ± 13.68 ng/ml/120 min; HP = 92.77 ± 17.44 ng/ml/120 min). The high protein diet group experienced a delayed glucose response for the first (SC = 30 min at 112 ± 7 mg/dl; HP = 60 min at 101 ± 5 mg/dl) and second OGTT (SC = 15 min at 117 ± 5 mg/dl; HP = 60 min at 95 ± 7 mg/dl). Body mass increased to the same extent in each diet group from the initial to final weighing (SC = 159 ± 2 g to 254 ± 7 g; HP = 157 ± 2 g to 242 ± 7 g). Despite a delay in peak glucose response, these findings suggest that glucose tolerance and body mass were neither adversely nor positively affected by a high protein diet.