Retinal microvascular calibre and risk of incident diabetes: the multi-ethnic study of atherosclerosis.

Aim: To prospectively examine the association of retinal microvascular signs with incident diabetes and impaired fasting glucose (IFG) in a multi-ethnic population-based cohort.

Methods: The multi-ethnic study of atherosclerosis comprised Caucasians, African-Americans, Hispanics and Chinese aged 45-84 years. Retinal vascular calibre and retinopathy were quantified from baseline retinal photographs. Incident diabetes and IFG were ascertained prospectively.

Results: After a median follow-up of 3 years, 243 (4.9%) people developed diabetes and 565 (15.0%) developed IFG. After adjusting for known risk factors, participants with wider retinal arteriolar calibre had a higher risk of developing diabetes [HR: 1.60; 95% CI: 1.12-2.29, p=0.011 comparing highest with lowest arteriolar calibre tertile]. In ethnic subgroup analysis, the association between wider retinal arteriolar calibre and incident diabetes was stronger and statistically significant only in Caucasians [HR: 2.78; 95% CI: 1.37-5.62, p=0.005]. Retinal venular calibre and retinopathy signs were not related to risk of diabetes or IFG.

Conclusion: Wider retinal arteriolar calibre is independently associated with an increased risk of diabetes, supporting a possible role for early arteriolar changes in diabetes development. This effect was largely seen in Caucasians, and not in other ethnic groups, and may reflect ethnic differences in susceptibility to diabetes from microvascular pathways.