THE EFFECT OF A HIGH-CARBOHYDRATE DIET ON GLUCOSE, INSULIN SENSITIVITY AND PLASMA INSULIN IN RATS

SUMMARY When groups of rats were kept on control and high-carbohydrate diets from the end of lactation until their body weight reached 150 g. it was found that the animals fed on the high-carbohydrate diet gained weight more rapidly, with an increase in fat deposits. Glucose and plasma insulin in both groups were compared with the amounts of hormone extracted from their pancreases. When the rats on the control diet were killed the insulin and glucose plasma levels were 40 ± 3 μu./ml. and 156·69 ± 13 mg./100 ml. respectively. After 17–20 hr. fasting these values decreased significantly ( P < 0·01) to 18 ± 1·5 μu./ml. and 116 ± 13 mg./ml. The amount of insulin in the pancreas was not modified by fasting. In the rats fed on the high-carbohydrate diet the plasma insulin and glucose values were higher than those in the control rats (50 ± 3·8 μu./ml. and 187 ± 19 mg./100 ml.); after 17–20 hr. starvation the glucose levels were reduced and the plasma insulin concentration remained higher (44 ± 2·9 μu./ml.); the insulin content of the pancreas was higher than in the control rats. In vitro the epididymal fat and the diaphragm of the rats on the high-carbohydrate diet were less sensitive to insulin than the same tissues in the controls.