Why Diabetic Retinopathy Can Develop Even With Good Blood Sugar Control

Lynn Valley Optometry
14 minutes ago
3 min read

By Dr. Leena Panaich, Optometrist at Lynn Valley Optometry

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One of the most common questions from patients living with diabetes is:

“If my blood sugar is well controlled, why am I showing signs of diabetic retinopathy?”

It can feel confusing — especially when you’re doing everything right. But diabetic retinopathy is influenced by many factors beyond blood glucose alone. In many cases, retinal changes begin quietly and long before vision is affected.

My goal is to help you understand why this happens, what’s going on inside the eye, and how we can protect your sight together.

What Is Diabetic Retinopathy?

Diabetic retinopathy is a condition where elevated blood sugar gradually damages the tiny blood vessels that supply the retina. These vessels can weaken, leak, or become blocked, which affects how well the retina can function and, over time, can impact your vision.

How It Develops

Early vessel changes: Small weak spots called microaneurysms form. These don’t cause symptoms but are visible on retinal imaging.
Leakage: Fragile vessels may leak small amounts of blood or fluid, causing swelling or deposits.
Reduced oxygen: When vessels close off, parts of the retina don’t receive enough oxygen.
New vessel growth: In advanced stages, the retina may grow fragile new vessels that bleed easily and can lead to scarring.

Macular Involvement

If fluid leaks into the macula — the area responsible for sharp, detailed vision — it can cause diabetic macular edema, one of the most common reasons diabetes leads to blurred or distorted vision.

The Four Stages

Mild Non-Proliferative Retinopathy: Early microaneurysms, no symptoms.
Moderate Non-Proliferative Retinopathy: Increased leakage and blood vessel changes.
Severe Non-Proliferative Retinopathy: Many blocked vessels, reduced oxygen.
Proliferative Diabetic Retinopathy: New vessel growth and higher risk of bleeding or detachment.

Why Retinopathy Can Develop Even With Good Blood Sugar Control

Even with strong habits and stable A1C levels, diabetic retinopathy can still develop. Blood sugar matters, but it’s not the only factor influencing retinal health.

1. Changes Often Begin Before Diagnosis

Many people have elevated blood sugar for years before diabetes is officially diagnosed, meaning early retinal stress may already be present.

2. A1C Doesn’t Capture Daily Fluctuations

An A1C is an average — it doesn’t show the spikes and drops that still place strain on the retinal blood vessels.

3. Duration of Diabetes Matters

The longer you’ve had diabetes, the greater the cumulative impact on the retinal vessels, even with excellent control.

4. Other Health Factors Play a Significant Role

High blood pressure, cholesterol, kidney disease, inflammation, and smoking all contribute to how vulnerable the retina is to damage.

5. Individual Biology Differs

Some people are simply more prone to microvascular changes. This isn’t a sign of doing something wrong — it’s how their retinal vessels respond.

6. Early Retinopathy Has No Symptoms

Vision can feel perfectly normal while changes are already happening, which is why imaging-based diabetic eye exams are essential.

How We Monitor and Protect Your Vision

At Lynn Valley Optometry, we use advanced retinal imaging to detect changes long before they affect your sight. These tools help evaluate your retinal health with precision and monitor subtle changes over time.

Optical Coherence Tomography (OCT): Detailed cross-sectional images of the retina allow us to see swelling, fluid, or structural changes.
Widefield Retinal Imaging: A panoramic view helps detect early leaks, vessel closure, or small hemorrhages.
Macular and Optic Nerve Assessment: Essential for monitoring diabetic macular edema and evaluating glaucoma risk.
Tear Film and Corneal Evaluation: Diabetes can affect the ocular surface, leading to dryness and fluctuating vision.

These technologies allow us to detect early changes, guide long-term care, and intervene when needed — well before vision is affected.

When to Seek Immediate Care

Book an exam promptly if you notice:

blurred or fluctuating vision
dark spots, floaters, or flashes
difficulty seeing at night
distortion or missing areas in your vision
sudden changes in colour perception

These may indicate swelling or bleeding in the retina.

Protecting Your Vision Long-Term

Having diabetes does not mean you will lose your vision. With early detection, consistent monitoring, and coordinated care, most patients maintain healthy sight throughout their lives — even if mild retinopathy develops.

My goal is always to help you understand what’s happening in your eyes, support your overall health, and protect your vision for the long term.