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

Aims – To examine the changes in glycaemic excursions which occur during pregnancy using continuous glucose monitoring and to compare patterns of glycaemia in pregnant women with type 1 and type 2 diabetes. Research design and methods – Observational data analysis from a prospective randomised study of continuous glucose monitoring in 57 women with pregestational type 1 (n=40) or type 2 diabetes (n=17) with 7-day CGMS profiles during each trimester. Serial glucose measurements were divided into periods of euglycaemia (70-140mg/dl), hyperglycaemia (>140mg/dl) and hypoglycaemia (< 70mg/dl). Generalised linear mixed effects models were fitted to the repeated measures data to determine how these glycaemic characteristics varied during gestation and by diabetes type. Results – 180 continuous glucose profiles were examined (140 type 1 diabetes, 40 type 2 diabetes) providing 20,433 hours of data for analysis (16,117 hours type 1 diabetes, 4,316 type 2 diabetes). Women with type 2 diabetes spend ∼33% less time hyperglycaemic throughout pregnancy compared to women with type 1 diabetes (p=0.005), with a significantly more rapid reduction in time spent hyperglycaemic in early pregnancy (p=0.02). Although women with type 2 diabetes spend less overall time hypoglycaemic (p=0.04), their risk of nocturnal hypoglycaemia is equivalent to women with type 1diabetes (BGL<70mg/dl, p = 0.9; BGL<50mg/dl, p = 0.2). Conclusions – Continuous glucose monitoring reveals clear differences in the level of glycaemic control that exist in women with type 1 and type 2 diabetes. These data will guide therapeutic interventions aimed at optimising glycaemic control and improving the pregnancy outcomes of both type 1 and type 2 diabetes.