Fasting Blood Glucose Levels and Initiation of Insulin Therapy in Gestational Diabetes

Abstract

To determine whether an initial fasting blood glucose determination will predict which pregnant women will need insulin in addition to dietary measures to maintain fasting glucose levels during gestation. All women referred for management of gestational diabetes received dietary counseling and instructions for self-monitoring of blood glucose levels during fasting and at 2 hours after each meal. Insulin therapy was initiated if the fasting blood glucose value exceeded 5.8 mmol/L (105 mg/dL) on more than one occasion, the 2-hour postprandial glucose exceeded 8.3 mmol/L (150 mg/dL), or the 2-hour postprandial glucose exceeded 6.7 mmol/L (120 mg/dL) three times in a week. The use of diet alone or diet plus insulin therapy was determined by review of medical records. Fifty-two pregnant women with fasting blood glucose levels of less than 5.8 mmol/L (105 mg/dL) and with two or more elevated blood glucose values on a 3-hour glucose tolerance test underwent follow-up at least through the 36th week of gestation. In 21 patients, insulin therapy was initiated in addition to diet. Two of five women with an initial fasting glucose level of less than 4.4 mmol/L (80 mg/dL) required insulin, and 8 of 24 women with fasting levels of 5.3 to 5.8 mmol/L (96 to 105 mg/dL) eventually needed insulin. The height of the fasting blood glucose level in women with gestational diabetes does not separate those who will maintain blood glucose levels in the targeted therapeutic range on diet alone from those who will need insulin. Therefore, all women with gestational diabetes need to participate in self-monitoring of blood glucose levels.