Poor blood sugar control leads to a higher incidence of vision loss among blacks with type 1 diabetes compared with their white counterparts, a new study shows.

According to research published in the Archives of Ophthalmology, older age, presence of proteinuria, and diabetic retinopathy (DR) were also predicting factors in vision loss for black patients.1

Monique S. Roy, MD, and colleagues from the University of Medicine and Dentistry of New Jersey in Newark, followed 483 blacks with type 1 diabetes to examine the incidence of visual loss and associated risk factors (see Figure 1). Patients were drawn from the New Jersey 725 study and reexamined after 6 years.

At follow-up, Dr. Roy and her colleagues found that 4.3% of patients developed visual loss in their better eye (visual acuity of 20/40 or worse), and 0.6% became blind (visual acuity of 20/200 or worse). Another 9.8% reportedly developed doubling of the visual angle (DVA), defined as a loss of 15 or more letters, in their better eye. An additional 13.5% developed DVA in either eye.

INCIDENCE OF DVA
The authors found that the incidence of DVA in either eye was 1.3% for patients who had diabetes for <5 years at baseline compared with 33.3% of patients who had diabetes for ≥30 years (P<.001). DVA in either eye was also significantly associated with age at diagnosis (age ≥13 years), higher A1C levels, higher systolic and diastolic blood pressure measurements, presence of proteinuria, macroangiopathy, and total and LDL cholesterol levels (see, Depression Impacts Vision Loss in Blacks With Type 1 Diabetes).

There were no significant associations, however, with level of education, socioeconomic, employment, or martial status, family or personal annual income, body mass index, smoking, alcohol consumption, or eye insurance coverage.

POOR CONTROL AT BASELINE
Other factors, including poor glycemic control at baseline and proteinuria were also significant predictors for vision loss. “Among African American patients, those in the upper quartile of [A1C] values at baseline had eight to 20 times the odds for progression to proliferative diabetic retinopathy at the 6-year follow-up than did patients in the lowest quartile,” the authors added. Because poor glycemic control is a well-established risk factor for visual loss “improving glycemic control in this population is critical for reducing visual loss,” they wrote.

Additionally, “microproteinuria, which is detected within a few years of the diagnosis of diabetes, seems to precede retinopathy and is a major predictor of mortality, particularly in men,” Dr. Roy and colleagues continued. “DR severity at baseline, however, was a stronger predictor of visual loss than was proteinuria . . . Thus, patients diagnosed as having proliferative DR should be evaluated for the presence of proteinuria.”

Monique S. Roy, MD, is from the University of Medicine and Dentistry, New Jersey Medical School, Institute of Ophthalmology and Visual Science, in Newark, New Jersey. She may be reached at roymo@umdnj.edu.

1. Roy MS, Skurnick J. Six-year incidence of visual loss in African Americans with type 1 diabete mellitus. Arch Ophthalmol. 2007;125:1061-1067.