Comparison of the retinal microvasculature in European and African-Caribbean people with diabetes
Résumé
Background: Diabetes aggravates the impact of elevated BP on the microcirculation and people of African-Caribbean origin with diabetes are more susceptible to microvascular damage than Europeans. We investigated possible differences in the retinal microcirculation in people of European and African Caribbean ethnicity with diabetes that might account for this. Methods: 51 subjects with type 2 diabetes (age 40-65yrs; 25 male; 29 African-Caribbean) were studied. Clinic and 24 hour ambulatory BP, fasting glucose, insulin, and lipids were measured. Digital retinal images were analysed using custom written semi-automatic software to determine: length:diameter ratio (LDR) and arteriolar:venular diameters (AVR), branching angles, vessel tortuosity and number of terminal vessel branches. Data are means (SD). Results: Arterioles were narrower in European people with diabetes than in African Caribbean people with diabetes (mean arteriolar diameter = 76 (7) vs. 82 (11) μm; p = 0.03; arteriolar LDR = 28.1 (8.5) vs. 23.7 (7.0); p = 0.046 and AVR = 0.66 (0.21) vs. 0.90 (0.36); p = 0.028). Ethnic differences in arteriolar LDR, arteriolar diameter and AVR were not explained by differences in BP but were attenuated by adjustment for duration of diabetes. There was no significant relationship between BP and arteriolar narrowing in the group as a whole, although the relationship between arteriolar LDR and SBP was stronger in Europeans than African-Caribbeans (β = 0.08 (0.07) vs. β = 0.03 (0.06); p = 0.032). Conclusions: In the presence of diabetes, a relationship between BP and retinal arteriolar diameter is not evident and implies impaired small artery remodelling in the presence of diabetes. African Caribbean people with diabetes have wider retinal arterioles and this could contribute to enhanced microvascular damage in this ethnic group.
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