Risk factors for the development of retinopathy in pre-diabetes and type 2 diabetes: The Diabetes Prevention Program experience

OBJECTIVE:

To determine glycemic and non-glycemic risk factors that contribute to the presence of diabetic retinopathy (DR) before and after the onset of type 2 diabetes (T2D).

RESEARCH DESIGN AND METHODS:

During the Diabetes Prevention Program (DPP) and DPP Outcome Study (DPPOS), we performed fundus photography over time on adults at high risk to develop T2D, including after they developed diabetes. Fundus photographs were graded using the ETDRS grading system with DR defined as typical lesions of DR (microaneurysms, exudates or hemorrhage, or worse) in either eye.

RESULTS:

By DPPOS year 16 (approximately 20 years after randomization into DPP), 24% of 1,614 who had developed T2D and 14% of 885 who remained non-diabetic had DR. In univariate analyses, utilizing results from across the entire duration of follow-up, American Indian race was associated with less frequent DR compared to Non-Hispanic Whites (NHW), and higher HbA1c, fasting and 2-hour plasma glucose levels during an oral glucose tolerance test, weight, and history of hypertension, dyslipidemia and smoking, but not treatment group assignment, were associated with more frequent DR. On multivariate analysis, American Indian race was associated with less DR compared to NHW (OR = 0.36; 95% CI: 0.20-0.66) and average HbA1c was associated with more DR (OR = 1.92; 95% CI: 1.46-1.74 per SD [0.7%] increase in HbA1c).

CONCLUSION:

DR may occur in adults with prediabetes and early in the course of T2D. HbA1c was an important risk factor for the development of DR across the entire glycemic range from prediabetes to T2D.