Hemoglobin A1c and fasting plasma glucose levels as predictors of retinopathy at 10 years: the French DESIR study.

OBJECTIVE: To evaluate the predictive values of hemoglobin A(1c) (HbA(1c)) and fasting plasma glucose (FPG) for retinopathy 10 years after the baseline examination.

METHODS: Seven hundred men and women from the DESIR (Data From an Epidemiological Study on the Insulin Resistance Syndrome) Study underwent evaluation for retinopathy using a nonmydriatic digital camera. During the preceding 9 years, 235 had diabetes mellitus (treated or FPG level of ≥126 mg/dL at least once), 227 had an impaired FPG level (110-125 mg/dL) at least once, and 238 always had glucose levels within reference limits (<110 mg/dL).

RESULTS: Compared with those without retinopathy, the 44 participants with retinopathy at 10 years had higher baseline mean (SD) levels of FPG (130 [49] vs 106 [22] mg/dL) and HbA(1c) (6.4% [1.6%] vs 5.7% [0.7%]) (both, P < .001). The frequency of retinopathy at 10 years, standardized according to the distribution of glycemia across the entire DESIR population, was 3.6%. In our population, FPG levels of 108 and 116 mg/dL had positive predictive values of 8.4% and 14.0%, respectively, for retinopathy at 10 years; HbA(1c) levels of 6.0% and 6.5% had positive predictive values of 6.0% and 14.8%, respectively. After 10 years of follow-up, retinopathy was equally frequent in participants with impaired FPG levels and in those who became diabetic during the study (8.6% and 6.7%, respectively), lower than in those with diabetes at baseline (13.9%).

CONCLUSION: Because the positive predictive values for retinopathy increase sharply from 108 mg/dL for FPG and from 6.0% for HbA(1c) levels, these thresholds are proposed to identify those at risk of retinopathy 10 years later.