Women who have either type 1 or type 2 diabetes before they become pregnant have an increased risk of pregnancy loss, high birthweight babies and perinatal deaths. The metabolic disruptions to the fetus caused by the mother's high blood sugars and insulin resistance can affect the development of organs, and cardiovascular malformations are the most common birth defects in infants born to diabetic mothers. Infants of diabetic mothers may also be at increased risk of developing obesity and type 2 diabetes. Management of diabetes in pregnancy therefore aims for tight control of glucose (glycaemic control) using careful combinations of diet, exercise, insulin or other anti-diabetogenic drugs, clinical visits and monitoring.
We identified only three small trials (in a total of 223 pregnant women with type 1 diabetes) looking at different intensities of glycaemic control.
We found very few differences between very tight and tight to moderate glucose targets in two trials, although there were significantly more cases of low blood sugar (hypoglycaemia) and longer hospital stays with very tight blood sugar control targets.
A single trial comparing tight, moderate and loose blood glucose targets found few differences between the tight and moderate groups, although significantly more women in the tight control group had hypoglycaemia in the first half of pregnancy. In the loose control group, significantly more women had pre-eclampsia, and there were significantly more caesareans and large babies.
It is clearly difficult for women to achieve glucose targets in isolation, and interventions such as monitoring may be successful in helping women to manage their diabetes.