Gestational retinal microvasculature and the risk of 5 year postpartum abnormal glucose metabolism

Changes in retinal microvasculature may reflect insulin resistance. We examined the association of changes in retinal microvasculature during pregnancy and risk of subsequent abnormal glucose metabolism in a cohort of mothers at baseline and 5 years postpartum.

Of the participants from the Singapore birth cohort (Growing Up in Singapore Towards Healthy Outcomes [GUSTO]), 276 mothers attended both baseline (at 26-28 weeks of gestation) and follow-up (5 year postpartum) visits. At baseline we performed retinal photography and assessed retinal microvascular variables using a validated grading system. At follow-up, we assessed glucose tolerance using a 75 g OGTT. We defined abnormal glucose metabolism if participants: (1) had onset of gestational diabetes mellitus (GDM) in subsequent pregnancies within a 5 year follow-up period (n = 103) or (2) had prediabetes (impaired fasting glucose, impaired glucose tolerance or HbA_1c 5.7-6.4% [39-46 mmol/mol]) and diabetes diagnosed at the 5 year follow-up visit (n = 84), according to WHO guidelines.

The incidence of GDM in subsequent pregnancy and abnormal glucose metabolism 5 years postpartum was 25.2% and 30.4%, respectively. Each 10 μm widening in retinal venular calibre was associated with a significant risk of postpartum abnormal glucose metabolism (RR 1.2 [95% CI 1.0, 1.5]), independent of maternal age, college education, ethnicity, pre-pregnancy BMI and GDM at baseline. Narrower retinal arteriolar calibre and venular branching angle at baseline was associated with a higher insulin resistance index (1.4 [95% CI 1.1, 1.7] and 1.3 [95% CI 1.1, 1.6], respectively) at follow-up.

Retinal microvasculature in pregnant women was associated with abnormal glucose metabolism 5 years postpartum. Alteration of microvascular structure during pregnancy may signal subclinical changes that underlie the development of prediabetes and diabetes.