The relationship between carbohydrate intake and glucose tolerance in pregnant women

Objective.  We verified whether a misdiagnosis of gestational diabetes mellitus can result in pregnant women when glucose tolerance has deteriorated after a low-carbohydrate meal, and tried to elucidate the mechanism behind the different outcome of the test. Study design.  Twenty-seven pregnant women were given directions for their evening meal the day before each of two 75-g oral glucose tolerance tests (OGTT). The evening meal was either a low-carbohydrate meal (carbohydrate, 6.7%; Low), or a high-carbohydrate meal (carbohydrate, 85.7%; High). Results.  The OGTT showed that the glucose tolerance was significantly impaired after Low than after High, with a significant increase of fasting plasma non-esterified fatty acids (NEFA) level. Moreover, the insulinogenic index (I-I) after High significantly decreased than that after Low. Conclusions.  The present data suggests that there is a risk of misdiagnosis of impaired glucose tolerance with only one intake of this extremely low-carbohydrate meal on the evening before testing. The decrease of insulin secretion and the activation of glucose-fatty acid cycle may be considered as the mechanism.