Don’t Lose Sight! Know the Truth About Diabetic Retinopathy

A Real Case to Begin With

A 56-year-old man visited the clinic, not primarily for sugar control, but due to an alarming eye complication. His ophthalmologist had referred him after being diagnosed with bilateral severe proliferative diabetic retinopathy (PDR) and clinically significant macular edema in his right eye.

His reports showed:

• HbA1c: 9.6%
  
• Fasting Blood Sugar: 256 mg/dL
  
• Postprandial: 302 mg/dL

He was already on a combination of metformin, glimepiride, pioglitazone, gliptin, calcium channel blockers, and multivitamins. The challenge was to rationalise this treatment plan and prevent further vision loss.

Click Here to Watch: Don’t Lose Sight! Know the Truth About Diabetic Retinopathy

Step 1: Stopping Pioglitazone

Pioglitazone is known to cause fluid retention, which can worsen macular edema. In a patient with severe eye involvement, this drug should be discontinued immediately. Its continued use could accelerate retinal swelling and further impair vision.

Step 2: Can Gliptins Be Used?

Gliptins are generally considered weight-neutral and can be continued if there is no contraindication. However, in long-standing diabetes with high insulin resistance, their benefit may be limited. Still, they are a relatively safe option to maintain stable glycemic control.

Step 3: Assess Kidney Function Before Continuing Metformin

Severe diabetic retinopathy often coexists with diabetic nephropathy. Before adjusting the metformin dose, it’s important to evaluate serum creatinine and eGFR levels. If kidney function remains within safe limits, metformin can be continued and even titrated upward if necessary.

Step 4: Introducing Insulin — Go Slow

In such cases, insulin therapy should be started gradually. Aggressive correction of blood sugar can paradoxically worsen macular edema and accelerate proliferative changes due to insulin’s cross-activity with IGF-1 receptors.

A basal insulin regimen works best here. The aim should be slow, steady improvement in glucose levels rather than rapid normalization.

Step 5: Other Oral Agents and Add-Ons

• Sulfonylureas can be continued.
  
• SGLT-2 inhibitors can be added since they help lower fasting and postprandial sugars without worsening retinopathy.
  
• Semaglutide (a GLP-1 analogue) should be avoided because it has been associated with worsening of proliferative diabetic retinopathy.

Step 6: Supportive Management

Blood pressure and lipid control play a crucial role in protecting retinal health.

• Replace calcium channel blockers with angiotensin receptor blockers (ARBs) whenever possible. ARBs are known to slow the progression of diabetic retinopathy.
  
• Initiate statin therapy even if cholesterol levels appear normal, as it helps reduce retinal inflammation and vascular damage.

SGLT-2 Inhibitors and Diabetic Foot: Use with Caution

If the patient has an active diabetic foot ulcer or ongoing infection, SGLT-2 inhibitors should be temporarily discontinued. These drugs may increase the risk of ketoacidosis and thrombotic events due to dehydration.

Once the infection resolves, therapy can be safely resumed. In patients with a previous history of thrombosis, however, SGLT-2 inhibitors should be used cautiously or avoided altogether.

Understanding Diabetic Retinopathy

Diabetic Retinopathy (DR) is one of the most serious microvascular complications of diabetes. It generally appears after 15–20 years of poor glycemic control, although in Type 1 diabetes, it can occur much earlier.

The Four Key Mechanisms

1. Advanced Glycation End Product (AGE) accumulation
   
2. Inflammation
   
3. Oxidative stress
   
4. Neovascularization

All four processes are driven by persistent hyperglycemia, which damages the retinal microvasculature and triggers a cascade of changes leading to vision loss.

Types of Diabetic Retinopathy

1. Non-Proliferative Diabetic Retinopathy (NPDR):

In this early stage, no new blood vessels form. Instead, the existing vessels weaken, causing:

• Microaneurysms
  
• Dot and blot hemorrhages
  
• Cotton wool spots
  
• Hard exudates

These changes reflect damage to the retinal support cells, leading to increased vascular permeability and ischemia.

2. Proliferative Diabetic Retinopathy (PDR):

Due to severe oxygen deprivation, new fragile blood vessels begin to grow into the vitreous cavity. These vessels lack proper support and rupture easily, leading to vitreous hemorrhage and, eventually, tractional retinal detachment.

Classification Rules

• 3:1 rule: Microaneurysms in at least three quadrants
  
• 4:1 rule: Dot-blot hemorrhages in all four quadrants, with venous beading in two quadrants and IRMA in one

Diagnosis

Diagnosis is confirmed through:

• Fluorescein Angiography: Highlights areas of retinal leakage and edema.
  
• Optical Coherence Tomography (OCT): Provides high-resolution images showing intra-retinal and sub-retinal fluid, essential for grading macular edema and planning treatment.

Management Approach

1. Achieve Glycemic Stability:
   Gradual and consistent glucose control is key.
   
2. Control Blood Pressure and Lipids:
   ARBs and statins slow the disease process and improve retinal perfusion.
   
3. Ophthalmologic Interventions:
   
   • Laser Photocoagulation: Creates controlled retinal burns to reduce hypoxia and VEGF production.
     
   • Anti-VEGF Therapy: Intravitreal injections block abnormal vessel growth.
     
   • Vitrectomy: Used in advanced cases with vitreous hemorrhage or retinal detachment.

Special Considerations

Pregnancy can aggravate diabetic retinopathy due to hormonal influences and vascular changes. Therefore, women with diabetes should undergo a detailed eye evaluation before conception and during each trimester.

Key Takeaways

• Discontinue pioglitazone in any diabetic with macular edema.
  
• Avoid semaglutide in patients with proliferative retinopathy.
  
• Continue metformin after assessing kidney function.
  
• Use a combination of ARB and statin for vascular protection.
  
• Reduce glucose levels gradually, not abruptly.
  
• Schedule annual fundus examinations for all diabetic patients.

Conclusion

Diabetic retinopathy is not just an eye disorder—it reflects the long-term damage diabetes causes throughout the body. Preventing or delaying it depends entirely on early detection, good sugar control, and timely ophthalmologic care.

Consistent monitoring, appropriate medications, and patient awareness can make all the difference between lasting vision and irreversible loss.

Take care of your eyes by controlling your sugars before it’s too late.