Objective
To evaluate the influence of Insulin-like Growth factor-I (IGF-I) and Placental Growth Hormone (GH) on progression of diabetic retinopathy during pregnancy in women with type 1 diabetes.

Design
Observational study of 88 consecutive pregnant women with type 1 diabetes for median 16.5 years (range 1–36) and HbA1c 6.6% (5.2–10.5) in early pregnancy. At 8, 14, 21, 27 and 33 weeks blood samples were drawn for measurement of IGF-I, placental GH and Hemoglobin A1c (HbA1c) and blood pressure was recorded. Fundus photography was performed at 8 and 27 weeks. Diabetic retinopathy was classified in five stages. Progression was defined as deterioration of at least one stage of diabetic retinopathy and/or development of macular edema on at least one eye.

Results
Placental GH and IGF-I levels increased throughout pregnancy and new onset or progression of diabetic retinopathy occurred in 22 (25%). A steeper increase in women with progression of diabetic retinopathy resulted in higher IGF-I levels at 27 weeks (p = 0.01) and 16% higher IGF-I levels throughout pregnancy (p = 0.02) compared with women without progression while similar levels of placental GH (p = 0.58) and HbA1c (p = 0.85) were observed throughout pregnancy. In a multivariate logistic regression analysis, progression of diabetic retinopathy was associated with higher IGF-I levels at 33 weeks (odds ratio 2.0 [95% confidence interval 1.1–3.6], p = 0.02) and higher systolic blood pressure at 8 weeks (1.9 [1.1–3.2], p = 0.02) independent of placental GH and HbA1c levels.

Conclusions
Pregnancy-induced increase in IGF-I levels is associated with progression of diabetic retinopathy in women with type 1 diabetes.