Retinopathy occurs via a variety of mechanisms, including disruption of the autoregulation of retinal blood flow, accumulation of sorbitol in the retina, and accumulation of advanced glycosylation end products in extracellular fluid. Advanced retinopathy, including neovascularization and proliferative changes, may be mediated by growth factors such as insulin growth factor 1 or vascular endothelial growth factor. Both pregnancy and intensive insulin therapy have been associated with advancing diabetic retinopathy.1,2 Factors that affect progression of retinopathy during pregnancy include the severity of retinopathy prior to pregnancy, duration of diabetes, use of more intensive therapy to decrease the rate of maternal and fetal complications of hyperglycemia, smoking, and presence of hypertension, hyperlipidemia, or hypoglycemia.3 Increased, not decreased, HbA1c values during the first trimester are associated with a high risk of major congenital malformations and miscarriage.4 Coronary vasospasm is not associated with improvements in glycemic control. Pregnancy and improved glycemic control will not accelerate the progression of diabetic nephropathy in women with mild renal dysfunction.1
- Progression of diabetic retinopathy.
1. Effect of pregnancy on microvascular complications in the diabetes control and complications trial. Diabetes Control and Complications Trial Research Group. Diabetes Care 2000;23:1084–91.
2. The effect of intensive treatment of diabetes on the development and progression of long-term complications in insulin-dependent diabetes mellitus. The Diabetes Control and Complications Trial Research Group. N Engl J Med 1993;329:977–86.
3. Chew EY, Mills JL, Metzger BE, et al. Metabolic control and progression of retinopathy. The Diabetes in Early Pregnancy Study. National Institute of Child Health and Human Development Diabetes in Early Pregnancy Study. Diabetes Care 1995;18:631–7.
4. Greene MF, Hare JW, Cloherty JP, et al. First-trimester hemoglobin A1 and risk for major malformation and spontaneous abortion in diabetic pregnancy. Teratology 1989;39:225–31.
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