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

Abstract

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 HbA(1c) 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 A(1c) (HbA(1c)) 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 HbA(1c) (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 HbA(1c) levels.

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