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A. Tirsi, M. Cho, W. Tsui, D. Nunez, C. Lee, A. Convit; Retinal Vascular Caliber, Obesity, and T2DM in Adolescents. Invest. Ophthalmol. Vis. Sci. 2008;49(13):4243.
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© ARVO (1962-2015); The Authors (2016-present)
In studies of adults, changes in retinal vascular caliber have been linked to obesity, insulin resistance (IR), and type 2 diabetes mellitus (T2DM). In adolescents, there is only some literature demonstrating the effect of obesity to vein caliber, but no information on how T2DM in obese adolescents may modify these associations. We examined the associations of retinal vascular diameters with Body Mass Index (BMI), inflammatory markers, and brain atrophy across three groups of adolescents: lean healthy controls, obese non-insulin resistant adolescents, and obese adolescents with T2DM.
We evaluated 11 lean adolescents (BMI of 22.9±3 kg/m2, 17.5±1.6 years of age, and 36% female), 10 non-IR obese controls (BMI of 37.0±7.3 kg/m2, 17.5±2.0 years of age, and 60% female), and 7 obese adolescents with T2DM (BMI of 35.7±8 kg/m2, 17.1±2.4 years of age, and 57% female). All adolescents underwent medical evaluation, and non-mydriatic fundus photography. Utilizing image analysis software developed in-house, Central retinal Venular Equivalent (CRVE) and Central retinal Arteriolar Equivalent (CRAE), which were then used to compute the Arteriole-to-venule Ratio (AVR), were measured using published procedures blind to subject characteristics.
Lean adolescents differed significantly in AVR from both obese adolescents with T2DM (0.75±0.6 vs 0.59±0.04) and non-IR obese controls (0.75±0.6 vs 0.6±0.04), both p < 0.05). When we ascertained how these AVR differences came about by assessing the differences between groups in CRAE and CRVE we found that lean controls, as expected, had significantly smaller CRVE than obese non-IR adolescents (278± 45.1 vs. 320± 48.1), whereas the low AVR among the obese adolescents with T2DM was being driven by a smaller CRAE in that group (204.9±25.8 vs. 180.2±9.7).After controlling for age and systolic blood pressure, there were significant associations between BMI and AVR (par r = -0.61, p = 0.003, df = 19). Using a linear regression model and after accounting for age and systolic blood pressure, BMI explained 33% of the adjusted variance in AVR.
AVR is decreased in both obese adolescents with T2DM and obese non-IR adolescents relative to lean adolescents, but through different mechanisms. As expected, retinal veins are enlarged in obesity whereas arteries are affected by the metabolic dysregulation of T2DM and are significantly reduced. Assessment of these associations in adolescents evaluated longitudinally may help clarify the mechanism.
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