NIH-supported clinical trials have shown that tight control of blood sugar levels prevents or delays the complications of diabetes. Here we see that tight control of blood sugar can prevent diabetic eye disease. This is data from the landmark Diabetes Control and Complications Trial (DCCT) was a clinical trial sponsored by the NIDDK between 1983 and 1993. In this trial, 1,441 patients with type 1 diabetes were randomized to either standard therapy or intensive control of blood glucose. This graph shows that, in patients who controlled their blood sugar aggressively, the risk of developing diabetic eye disease was 76 percent lower.

The findings of this trial paved the way to studies that replicated these impressive results in type 2 diabetes patients.