**Core Concept**
The question is testing the understanding of the increased risk of blindness in diabetic patients, particularly those with diabetic retinopathy, as compared to non-diabetic patients. Diabetic retinopathy is a microvascular complication of diabetes that can lead to vision impairment or blindness.

**Why the Correct Answer is Right**
The risk of blindness in diabetic patients is significantly higher due to the development of diabetic retinopathy, which is a leading cause of vision loss among working-age adults. In diabetic retinopathy, high blood sugar levels damage the blood vessels in the retina, leading to leakage, ischemia, and neovascularization. This can cause retinal detachment, macular edema, and vision loss. Studies have shown that diabetic patients are 25 times more likely to experience blindness compared to non-diabetic patients.

**Why Each Wrong Option is Incorrect**
**Option A:** 5 times - This is an underestimation of the actual risk, as diabetic patients are more than 5 times more likely to experience blindness.
**Option B:** 10 times - While diabetic patients are at increased risk, this option is still an underestimation compared to the correct answer.
**Option C:** 15 times - This option is closer to the correct answer but still an underestimation of the actual risk.

**Clinical Pearl / High-Yield Fact**
It's essential to note that early detection and treatment of diabetic retinopathy can significantly reduce the risk of blindness. Patients with diabetes should undergo regular eye exams to detect any signs of diabetic retinopathy, and prompt treatment can help preserve vision.

**✓ Correct Answer: D. 25 times**