Effect of feeding a high-fat diet during pregnancy on glucose metabolism in the rat

Abstract

To alter glucose homeostasis in a period of great glucose demand, pregnant rats were submitted to a high-fat diet and compared to virgin rats. In virgin rats, blood glucose, ketone bodies, plasma insulin, and free fatty acids were not affected by the diet consumed. Glucose turnover measured in the postabsorptive period was slightly decreased in virgin rats fed a high-fat diet compared to rats fed a standard diet. Assuming that the glucose turnover rate is representative for the 24-hour average endogenous glucose production, in rats fed a standard diet the daily carbohydrate intake (9.2 ± 0.7 g/d) exceeded the glucose turnover rate (4 ± 0.2 g/d) and could meet the glucose requirement. In rats fed a high-fat diet the carbohydrate intake (2.7 ± 0.2 g/d) was lower than the glucose turnover rate (3.8 ± 0.2 g/d), which demonstrated the need for an active endogenous glucose production. Blood glucose, ketone bodies, plasma insulin, and free fatty acid concentrations followed the same patterns during pregnancy in rats fed a standard diet compared to rats fed a high-fat diet. The glucose turnover rate in the postabsorptive period was no more decreased by the high-fat diet in pregnant rats compared to virgin rats despite the greater glucose demand. In late pregnancy the glucose turnover rate was increased up to 70%. Assuming that the glucose turnover rate is representative of the 24-hour average endogenous glucose production, the difference of daily carbohydrate intake 13 ± 1 g/d for the standard diet and 3.7 ± 0.2 g/d for the high-fat diet and of glucose turnover rates 6.1 ± 0.8 g/d and 5.8 ± 0.3 g/d suggest that (1) an increased endogenous glucose production and not a decreased glucose utilization occurred in rats fed a high-fat diet and (2) the endogenous glucose production must be increased twofold in pregnant rats fed a high-fat diet for maintaining glucose homeostasis.