Early retinal arteriolar changes and peripheral neuropathy in diabetes

OBJECTIVE - To examine the association between early retinal arteriolar abnormalities and diabetic peripheral neuropathy (DPN). RESEARCH DESIGN AND METHODS - Data from 608 people (aged 40-80 years) with diabetes from the population-based Singapore Malay Eye Study were analyzed. Participants underwent binocular two-field digital retinal photography and quantitative sensory testing. DPN was defined as an abnormal response to a monofilament or neurothesiometer test. Quantitative changes of retinal vascular caliber and arteriolar bifurcation geometry were measured using a computer-based program. Qualitative retinal signs of retinopathy and retinal arteriolar wall signs were graded by standardized methods. RESULTS - DPN was present in 155 people (25.5%). After adjusting for age, sex, diabetes duration, HbA1c, cardiovascular risk factors, antihypertensive medication use, and peripheral arterial disease, people with suboptimal arteriolar caliber (odds ratio 1.94 [95% CI 1.22-3.10]), larger arteriolar branching coefficient (1.58 [1.03-2.42]), diabetic retinopathy (1.82 [1.20-2.75]), and focal arteriolar narrowing (2.92 [1.48-5.76]) were more likely to have DPN. Participants with a greater number of retinal microvascular signs were more likely to have DPN than those without retinal changes (6.11 [2.11-17.71] for two or more signs and 3.47 [1.18-10.21] for one sign compared with none). CONCLUSIONS - Individuals with diabetes with early retinal arteriolar abnormalities are more likely to have DPN, independent of hyperglycemia and major vascular risk factors. These data support the hypothesis that early microvascular dysfunction, evident in the retina, is an independent risk factor for DPN