Do patients with type 2 diabetes mellitus (T2DM) require continued diabetic retinopathy screening if they achieve normoglycemia, indicated by a hemoglobin A1c (HbA1c) level below 5.5%, without the use of antidiabetic medication?

From the Guidelines

Type 2 diabetics should continue regular retinopathy screening even if they've improved their A1c below 5.5 without medication, with the recommended schedule typically being annual comprehensive eye exams, though this may be adjusted based on individual risk factors. The risk of diabetic retinopathy persists due to previous periods of hyperglycemia that may have already initiated damage to retinal blood vessels, as well as other factors beyond A1c, such as blood pressure, cholesterol levels, and diabetes duration, which contribute to retinopathy risk 1. The screening process is non-invasive, involving pupil dilation and examination of the retina to detect early changes before they affect vision. Early detection allows for timely intervention, potentially preventing vision loss. While improved glycemic control significantly reduces risk progression, it doesn't eliminate the need for ongoing surveillance, as retinopathy can develop silently without symptoms until advanced stages when treatment becomes less effective. According to the standards of medical care in diabetes-2019, if there is no evidence of retinopathy for one or more annual eye exams and glycemia is well controlled, then exams every 1–2 years may be considered 1. However, more frequent examinations by the ophthalmologist will be required if retinopathy is progressing.

Some studies suggest that less frequent screening intervals, such as every 2-3 years, may be adequate for patients with no prior retinopathy and well-controlled diabetes, but this should be determined on a case-by-case basis, taking into account individual risk factors and the presence of other complications 1. The American Diabetes Association recommends annual eye exams for patients with diabetes, unless advised by an eye care professional, due to concerns about patients being lost to follow-up and the possibility of coexisting ocular conditions such as glaucoma.

Key points to consider:

• Regular retinopathy screening is essential for type 2 diabetics, even with improved A1c levels
• The recommended screening schedule is typically annual, but may be adjusted based on individual risk factors
• Factors beyond A1c, such as blood pressure and cholesterol levels, contribute to retinopathy risk
• Early detection and timely intervention can potentially prevent vision loss
• The screening process is non-invasive and involves pupil dilation and examination of the retina.

From the Research

Retinopathy Screening for Type 2 Diabetics with Improved A1c Levels

• The need for continued retinopathy screening in type 2 diabetics who have improved their A1c levels below 5.5 without medication is supported by several studies 2, 3, 4, 5, 6.
• A study published in 2019 found that intensive glycaemic control can lead to early worsening of diabetic retinopathy and vision loss, highlighting the importance of regular ophthalmological review during periods of intensive glycaemic control 2.
• Another study from 2015 found that intensive glycemic control reduced the risks of retinal photocoagulation or vitrectomy, macular edema, and progression of retinopathy, but did not significantly reduce the risk of incidence of retinopathy or severe loss of vision or blindness 3.
• A 2021 study found that glycemic control sequentially restored the thickness and volume of some macular photoreceptor layers, but high glucose levels during glycemic control may lead to the development of diabetic retinopathy 4.
• A 2024 study found that retinal microvascular changes precede clinically apparent diabetic retinopathy and are closely related to glycemic control, with early choriocapillaris impairment associated with HbA1c levels 5.
• Overall, these studies suggest that type 2 diabetics who have improved their A1c levels below 5.5 without medication should still continue retinopathy screening to monitor for potential complications and ensure optimal visual outcomes 2, 3, 4, 5, 6.

Key Findings

• Intensive glycaemic control can lead to early worsening of diabetic retinopathy and vision loss 2.
• Glycemic control reduces the risk of most retinopathy-related events, but may not reduce the risk of incidence of retinopathy or severe loss of vision or blindness 3.
• Retinal microvascular changes precede clinically apparent diabetic retinopathy and are closely related to glycemic control 5.
• Glycemic control sequentially restores the thickness and volume of some macular photoreceptor layers, but high glucose levels during glycemic control may lead to the development of diabetic retinopathy 4.