Lower levels of circulating IGF‐I in Type 1 diabetic women with frequent severe hypoglycaemia during pregnancy

Aims Severe hypoglycaemia is a significant problem in pregnant women with Type 1 diabetes. We explored whether frequent severe hypoglycaemia during pregnancy in women with Type 1 diabetes is related to placental growth hormone (GH) and insulin‐like growth factor I (IGF‐I) levels. Methods A prospective, observational study of 107 consecutive pregnant women with Type 1 diabetes. Blood samples were drawn for IGF‐I and placental GH analyses at 8, 14, 21, 27 and 33 weeks. Severe hypoglycaemic events were reported within 24 h. Results Eleven women (10%) experienced frequent severe hypoglycaemia (≥ 5 events), accounting for 60% of all events. Throughout pregnancy, IGF‐I levels were 25% lower in these women (P < 0.005) compared with the remaining women, despite similar placental GH levels. Eighty per cent of the severe hypoglycaemic events occurred before 20 weeks when IGF‐I levels were at their lowest. This finding was not explained by differences in insulin dose, median plasma glucose levels or glycated haemoglobin. History of severe hypoglycaemia the year preceding pregnancy and impaired hypoglycaemia awareness—being the only predictors of frequent severe hypoglycaemia in a logistic regression analysis—were not associated with IGF‐I or placental GH levels at 8 weeks. Conclusions In women with Type 1 diabetes experiencing frequent severe hypoglycaemia during pregnancy, IGF‐I levels are significantly lower compared with the remaining women despite similar placental GH levels. IGF‐I levels are lowest in early pregnancy where the incidence of severe hypoglycaemia is highest. IGF‐I may be a novel factor of interest in the investigation of severe hypoglycaemia in patients with Type 1 diabetes.