Diabetes (high blood sugars) that develops during pregnancy is called Gestational Diabetes Mellitus (GDM). GDM is increasing, affecting one-in-eight pregnant women in Ireland. Women with GDM have an increased risk of complications at the time of delivery, including Caesarean section. Women with GDM have a 7-fold increased risk of diabetes long-term. Infants of mothers with GDM have a greater risk of being born overweight and require admission to neonatal intensive care units because of low blood sugars, and other medical complications. The first line of managing high blood sugar levels is diet and exercise. However, 40% of women with GDM will require insulin to maintain normal blood sugar levels. While insulin is effective at keeping blood sugars in the normal range, it has important side-effects and limitations for the mother (e.g. excessive weight gain, low blood sugars, delivery by caesarean section) and baby (tendency to excess weight). A potential other treatment is a tablet called metformin used for 30 years in diabetes and fertility treatment. In a GDM trial in New Zealand, metformin was shown to work as well as insulin and be safe during pregnancy. Metformin might also reduce the chance of women with GDM developing long term diabetes after pregnancy. Two trials are on-going examining metformin in overweight women without diabetes and in women with Type 2 diabetes during pregnancy. We wish to see if metformin is effective for all women with GDM (not just those who are obese) if given at the time of diagnosis in addition to diet and exercise management. We want to see also if metformin is associated with less excessive weight gain and need for insulin. This may translate into better pregnancy outcomes, reduce progression to Type 2 Diabetes for the mother and break the circle of future diabetes in the offspring.
