Changes in the glycemic profiles of women with type 1 and type 2 diabetes during pregnancy

OBJECTIVE - To examine the changes in glycemic excursions that occur during pregnancy using continuous glucose monitoring and to compare patterns of glycemia in pregnant women with type I and type 2 diabetes. RESEARCH DESIGN AND METHODS - An observational data analysis was performed from a prospective randomized study of continuous glucose monitoring in 57 women with pregestational type 1 (n = 40) or type 2 (n = 17) diabetes with 7-day continuous glucose monitoring system profiles during each trimester. Serial glucose measurements were divided into periods of euglycemia (70-140 mg/dl), hyperglycernia (>140 mg/dl), and hypoglycemia (<70 mg/dl). Generalized linear mixed effects models were fitted to the repeated measures data to determine how these glycemic characteristics varied during gestation and by diabetes type. RESULTS - A total of 180 continuous glucose profiles were examined (140 type I diabetes, 40 type 2 diabetes), providing 20,433 h of data for analysis (16,117 h type I diabetes, 4,316 type 2 diabetes). Women with type 2 diabetes spend similar to 33% less time hyperglycemic throughout pregnancy than women with type I diabetes (P = 0.005), with a significantly more rapid reduction in time spent hyperglycemic in early pregnancy (P = 0.02). Although women with type 2 diabetes spend less overall time hypoglycemic (P = 0.04), their risk of nocturnal hypoglycemia is equivalent to that of women with type 1 diabetes (blood glucose level <70 mg/dl, P = 0.9; blood glucose level <50 mg/dl, P = 0.2). CONCLUSIONS - Continuous glucose monitoring reveals clear differences in the level of glycemic control that exist in women with type 1 and type 2 diabetes. These data will guide therapeutic interventions aimed at optimizing glycemic control and improving the pregnancy outcomes of both type 1 and type 2 diabetes.